[Rust] Dependabot isn't able to find build.rs file

### Is there an existing issue for this?

- [x] I have searched the existing issues

### Package ecosystem

cargo

### Package manager version

_No response_

### Language version

Rust 1.86

### Manifest location and content before the Dependabot update

```
[package]
edition = "2021"
links = "hermes"
name = "libhermes-sys"
version = "0.14.0"

[dependencies]

[build-dependencies]
bindgen = { workspace = true }
cc = { workspace = true, features = ["parallel"] }

[package.metadata.workspaces]
independent = true

```

### dependabot.yml content

```
version: 2
updates:
- package-ecosystem: "cargo"
directory: "/" # Location of package manifests
schedule:
interval: "cron"
cronjob: "0 12 * * 6" #Saturday at 12:00 UTC
commit-message:
prefix: "chore"
include: "scope"
open-pull-requests-limit: 5
groups:
minor-and-patch:
update-types:
- "patch"
- "minor"
patterns:
- "*"
major:
update-types:
- "major"
patterns:
- "*"
```

### Updated dependency

_No response_

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

https://github.com/dependabot/feedback/issues/943

I looked around in the issues and saw that this was fixed, but it in my case it fails to parse the manifest because of a "missing" build.rs script

```
updater | 2025/06/14 12:49:18 INFO Updating cc from 1.2.26 to 1.2.27
updater | 2025/06/14 12:49:20 INFO Started process PID: 1549 with command: {} git config --global credential.helper '!/home/dependabot/common/lib/dependabot/../../bin/git-credential-store-immutable --file /home/dependabot/dependabot-updater/tmp/20250614-1283-su0btk/dependabot_20250614-1283-flarn0/git.store' {}
updater | 2025/06/14 12:49:20 INFO Process PID: 1549 completed with status: pid 1549 exit 0
updater | 2025/06/14 12:49:20 INFO Total execution time: 0.01 seconds
updater | 2025/06/14 12:49:20 INFO Started process PID: 1557 with command: {} git config --global --replace-all url.https://github.com/.insteadOf ssh://git@github.com/ {}
updater | 2025/06/14 12:49:20 INFO Process PID: 1557 completed with status: pid 1557 exit 0
2025/06/14 12:49:20 INFO Total execution time: 0.01 seconds
updater | 2025/06/14 12:49:20 INFO Started process PID: 1564 with command: {} git config --global --add url.https://github.com/.insteadOf ssh://git@github.com: {}
updater | 2025/06/14 12:49:20 INFO Process PID: 1564 completed with status: pid 1564 exit 0
2025/06/14 12:49:20 INFO Total execution time: 0.01 seconds
updater | 2025/06/14 12:49:20 INFO Started process PID: 1571 with command: {} git config --global --add url.https://github.com/.insteadOf git@github.com: {}
updater | 2025/06/14 12:49:20 INFO Process PID: 1571 completed with status: pid 1571 exit 0
2025/06/14 12:49:20 INFO Total execution time: 0.01 seconds
updater | 2025/06/14 12:49:20 INFO Started process PID: 1578 with command: {} git config --global --add url.https://github.com/.insteadOf git@github.com/ {}
updater | 2025/06/14 12:49:20 INFO Process PID: 1578 completed with status: pid 1578 exit 0
2025/06/14 12:49:20 INFO Total execution time: 0.01 seconds
updater | 2025/06/14 12:49:20 INFO Started process PID: 1585 with command: {} git config --global --add url.https://github.com/.insteadOf git://github.com/ {}
updater | 2025/06/14 12:49:20 INFO Process PID: 1585 completed with status: pid 1585 exit 0
2025/06/14 12:49:20 INFO Total execution time: 0.01 seconds
proxy | 2025/06/14 12:49:20 [947] POST /update_jobs/1034095978/record_update_job_unknown_error
proxy | 2025/06/14 12:49:20 [947] 204 /update_jobs/1034095978/record_update_job_unknown_error
proxy | 2025/06/14 12:49:20 [949] POST /update_jobs/1034095978/record_update_job_error
proxy | 2025/06/14 12:49:20 [949] 204 /update_jobs/1034095978/record_update_job_error
proxy | 2025/06/14 12:49:20 [951] POST /update_jobs/1034095978/increment_metric
proxy | 2025/06/14 12:49:20 [951] 204 /update_jobs/1034095978/increment_metric
proxy | 2025/06/14 12:49:20 [953] POST /update_jobs/1034095978/record_update_job_unknown_error
proxy | 2025/06/14 12:49:20 [953] 204 /update_jobs/1034095978/record_update_job_unknown_error
updater | 2025/06/14 12:49:20 ERROR Error processing cc (Dependabot::SharedHelpers::HelperSubprocessFailed)
2025/06/14 12:49:20 ERROR error: failed to load manifest for workspace member `dependabot_tmp_dir/cr-miner`
referenced by workspace at `dependabot_tmp_dir/Cargo.toml`

Caused by:
failed to load manifest for dependency `hermes-buffers`

Caused by:
failed to load manifest for dependency `hermes-rs`

Caused by:
failed to load manifest for dependency `libhermes-sys`

Caused by:
failed to parse manifest at `dependabot_tmp_dir/hermes-rs/libhermes-sys/Cargo.toml`

Caused by:
package specifies that it links to `hermes` but does not have a custom build script
```

### Native package manager behavior

CC updates just fine with cargo uppdate
```
* [new tag] cb-info@0.1.4 -> origin/tags/cb-info@0.1.4
Locking 36 packages to latest compatible versions
Updating adler2 v2.0.0 -> v2.0.1
Updating async-compression v0.4.23 -> v0.4.24
Updating base64ct v1.7.3 -> v1.8.0
Updating cc v1.2.26 -> v1.2.27
```

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

_No response_

### Smallest manifest that reproduces the issue

_No response_

Start by reproducing the Cargo update failure with the supplied dependabot.yml and manifest, then inspect the staged workspace and libhermes-sys/Cargo.toml around the missing build.rs error. Compare this with the native cargo update behavior; done means the cc update completes without the custom-build-script manifest failure.

Written by the indexing model from the issue text.