dependabot fails to update composer packages, returns "Requirements to unlock update_not_possible"

### Is there an existing issue for this?

- [X] I have searched the existing issues

### Package ecosystem

composer

### Package manager version

_No response_

### Language version

_No response_

### Manifest location and content before the Dependabot update

https://github.com/VerifiedJoseph/URLTeamStatsTracker/blob/master/composer.json
https://github.com/VerifiedJoseph/URLTeamStatsTracker/blob/master/composer.lock

### dependabot.yml content

```
version: 2
updates:
- package-ecosystem: "composer"
directory: "/"
schedule:
interval: "weekly"
- package-ecosystem: "github-actions"
directory: "/"
schedule:
interval: "weekly"
```

### Updated dependency

_No response_

### What you expected to see, versus what you actually saw

Dependabot to open PRs for:
- php-curl-class/php-curl-class (9.14.3 => 9.18.2)
- phpstan/phpstan (1.10.10 => 1.10.35)

Instead dependabot outputs:

```
Requirements to unlock update_not_possible
Requirements update strategy bump_versions_if_necessary
No update possible for [dependency] [version]`
```

Full dependabot log

```
proxy | 2023/09/23 20:01:31 proxy starting, commit: 93c4a893d794d736d84e940a79420e8d1180c0bd
proxy | 2023/09/23 20:01:31 Listening (:1080)
updater | 2023-09-23T20:01:31.642217499 [725447037:main:WARN:src/devices/src/legacy/serial.rs:222] Detached the serial input due to peer close/error.
updater | time="2023-09-23T20:01:33Z" level=info msg="guest starting" commit=b073e069d366dc2f68bb8ef0134feb3c29cacadd
updater | time="2023-09-23T20:01:33Z" level=info msg="starting job..." fetcher_timeout=10m0s job_id=725447037 updater_timeout=45m0s updater_version=17a2d9f19df617f557f23d001cbea428561e02e9-composer
updater | 2023/09/23 20:01:35 INFO Raven 3.1.2 ready to catch errors
updater | 2023/09/23 20:01:35 INFO Starting job processing
proxy | 2023/09/23 20:01:36 [002] GET https://api.github.com:443/repos/VerifiedJoseph/URLTeamStatsTracker
proxy | 2023/09/23 20:01:36 [002] * authenticating github api request with token for api.github.com
proxy | 2023/09/23 20:01:36 [002] 200 https://api.github.com:443/repos/VerifiedJoseph/URLTeamStatsTracker
proxy | 2023/09/23 20:01:36 [004] GET https://api.github.com:443/repos/VerifiedJoseph/URLTeamStatsTracker/git/refs/heads/master
proxy | 2023/09/23 20:01:36 [004] * authenticating github api request with token for api.github.com
proxy | 2023/09/23 20:01:36 [004] 200 https://api.github.com:443/repos/VerifiedJoseph/URLTeamStatsTracker/git/refs/heads/master
proxy | 2023/09/23 20:01:36 [006] GET https://api.github.com:443/repos/VerifiedJoseph/URLTeamStatsTracker/contents/composer.json?ref=dd8bb6015ccc605d581e35e6c1bfdc8ad4926cf0
proxy | 2023/09/23 20:01:36 [006] * authenticating github api request with token for api.github.com
proxy | 2023/09/23 20:01:36 [006] 200 https://api.github.com:443/repos/VerifiedJoseph/URLTeamStatsTracker/contents/composer.json?ref=dd8bb6015ccc605d581e35e6c1bfdc8ad4926cf0
proxy | 2023/09/23 20:01:36 [008] GET https://api.github.com:443/repos/VerifiedJoseph/URLTeamStatsTracker/contents/?ref=dd8bb6015ccc605d581e35e6c1bfdc8ad4926cf0
proxy | 2023/09/23 20:01:36 [008] * authenticating github api request with token for api.github.com
proxy | 2023/09/23 20:01:36 [008] 200 https://api.github.com:443/repos/VerifiedJoseph/URLTeamStatsTracker/contents/?ref=dd8bb6015ccc605d581e35e6c1bfdc8ad4926cf0
proxy | 2023/09/23 20:01:36 [010] GET https://api.github.com:443/repos/VerifiedJoseph/URLTeamStatsTracker/contents/composer.lock?ref=dd8bb6015ccc605d581e35e6c1bfdc8ad4926cf0
proxy | 2023/09/23 20:01:36 [010] * authenticating github api request with token for api.github.com
proxy | 2023/09/23 20:01:36 [010] 200 https://api.github.com:443/repos/VerifiedJoseph/URLTeamStatsTracker/contents/composer.lock?ref=dd8bb6015ccc605d581e35e6c1bfdc8ad4926cf0
updater | 2023/09/23 20:01:36 INFO Finished job processing
updater | time="2023-09-23T20:01:36Z" level=info msg="task complete" container_id=job-725447037-file-fetcher exit_code=0 job_id=725447037 step=fetcher
updater | 2023/09/23 20:01:37 INFO Raven 3.1.2 ready to catch errors
updater | 2023/09/23 20:01:38 INFO Starting job processing
updater | 2023/09/23 20:01:38 INFO Starting update job for VerifiedJoseph/URLTeamStatsTracker
updater | 2023/09/23 20:01:38 INFO Checking all dependencies for version updates...
updater | 2023/09/23 20:01:38 INFO Checking if squizlabs/php_codesniffer 3.7.2 needs updating
proxy | 2023/09/23 20:01:39 [018] GET https://repo.packagist.org:443/p2/squizlabs/php_codesniffer.json
proxy | 2023/09/23 20:01:39 [018] 200 https://repo.packagist.org:443/p2/squizlabs/php_codesniffer.json
updater | 2023/09/23 20:01:39 INFO Latest version is 3.7.2
updater | 2023/09/23 20:01:39 INFO No update needed for squizlabs/php_codesniffer 3.7.2
updater | 2023/09/23 20:01:39 INFO Checking if php-curl-class/php-curl-class 9.14.3 needs updating
proxy | 2023/09/23 20:01:39 [020] GET https://repo.packagist.org:443/p2/php-curl-class/php-curl-class.json
proxy | 2023/09/23 20:01:39 [020] 200 https://repo.packagist.org:443/p2/php-curl-class/php-curl-class.json
updater | 2023/09/23 20:01:39 INFO Latest version is 9.18.2
proxy | 2023/09/23 20:01:39 [022] GET https://repo.packagist.org:443/packages.json
proxy | 2023/09/23 20:01:39 [022] 200 https://repo.packagist.org:443/packages.json
proxy | 2023/09/23 20:01:39 [024] GET https://repo.packagist.org:443/p2/php-curl-class/php-curl-class.json
proxy | 2023/09/23 20:01:39 [024] 200 https://repo.packagist.org:443/p2/php-curl-class/php-curl-class.json
updater | 2023/09/23 20:01:39 INFO Requirements to unlock update_not_possible
updater | 2023/09/23 20:01:39 INFO Requirements update strategy bump_versions_if_necessary
updater | 2023/09/23 20:01:39 INFO No update possible for php-curl-class/php-curl-class 9.14.3
updater | 2023/09/23 20:01:39 INFO Checking if league/climate 3.8.2 needs updating
proxy | 2023/09/23 20:01:40 [026] GET https://repo.packagist.org:443/p2/league/climate.json
proxy | 2023/09/23 20:01:40 [026] 200 https://repo.packagist.org:443/p2/league/climate.json
updater | 2023/09/23 20:01:40 INFO Latest version is 3.8.2
updater | 2023/09/23 20:01:40 INFO No update needed for league/climate 3.8.2
updater | 2023/09/23 20:01:40 INFO Checking if phpstan/phpstan 1.10.10 needs updating
proxy | 2023/09/23 20:01:40 [028] GET https://repo.packagist.org:443/p2/phpstan/phpstan.json
proxy | 2023/09/23 20:01:40 [028] 200 https://repo.packagist.org:443/p2/phpstan/phpstan.json
updater | 2023/09/23 20:01:40 INFO Latest version is 1.10.35
proxy | 2023/09/23 20:01:40 [030] GET https://repo.packagist.org:443/packages.json
proxy | 2023/09/23 20:01:40 [030] 304 https://repo.packagist.org:443/packages.json
proxy | 2023/09/23 20:01:40 [032] GET https://repo.packagist.org:443/p2/phpstan/phpstan.json
proxy | 2023/09/23 20:01:40 [032] 200 https://repo.packagist.org:443/p2/phpstan/phpstan.json
updater | 2023/09/23 20:01:40 INFO Requirements to unlock update_not_possible
updater | 2023/09/23 20:01:40 INFO Requirements update strategy bump_versions_if_necessary
updater | 2023/09/23 20:01:40 INFO No update possible for phpstan/phpstan 1.10.10
updater | 2023/09/23 20:01:40 INFO Finished job processing
updater | time="2023-09-23T20:01:40Z" level=info msg="task complete" container_id=job-725447037-updater exit_code=0 job_id=725447037 step=updater

```

### Native package manager behavior

Composer running locally updates both dependencies.

```
> composer --version
Composer version 2.6.3 2023-09-15 09:38:21
```
```
> composer update phpstan/phpstan

Loading composer repositories with package information
Info from https://repo.packagist.org: #StandWithUkraine
Updating dependencies
Lock file operations: 0 installs, 1 update, 0 removals
- Upgrading phpstan/phpstan (1.10.10 => 1.10.35)
Writing lock file
Installing dependencies from lock file (including require-dev)
Package operations: 0 installs, 1 update, 0 removals
- Upgrading phpstan/phpstan (1.10.10 => 1.10.35): Extracting archive
Generating autoload files
1 package you are using is looking for funding.
Use the `composer fund` command to find out more!
No security vulnerability advisories found
```
```
> composer update php-curl-class/php-curl-class

Loading composer repositories with package information
Updating dependencies
Lock file operations: 0 installs, 1 update, 0 removals
- Upgrading php-curl-class/php-curl-class (9.14.3 => 9.18.2)
Writing lock file
Installing dependencies from lock file (including require-dev)
Package operations: 0 installs, 1 update, 0 removals
- Downloading php-curl-class/php-curl-class (9.18.2)
- Upgrading php-curl-class/php-curl-class (9.14.3 => 9.18.2): Extracting archive
Generating autoload files
1 package you are using is looking for funding.
Use the `composer fund` command to find out more!
No security vulnerability advisories found
```

### Images of the diff or a link to the PR, issue, or logs

_No response_

### Smallest manifest that reproduces the issue

_No response_

Start with the linked composer.json and composer.lock from VerifiedJoseph/URLTeamStatsTracker and compare Dependabot's composer updater logs with the successful local Composer 2.6.3 commands. Trace why php-curl-class/php-curl-class and phpstan/phpstan reach update_not_possible despite Composer updating them locally. Done means a reproducible diagnosis and a regression test or confirmed fix for these updates.

Written by the indexing model from the issue text.