Could not find pull request information for private repo

I'm using the docker image with GitHub Actions, and I'm getting a failure, but all the logs say is:

```
Executing $(which danger) ci --process danger-kotlin --passURLForDSL --failOnErrors --no-publish-check - pid 1
Request failed [403]: https://api.github.com/repos///pulls/
Response: {
"message": "Resource not accessible by integration",
"documentation_url": "https://docs.github.com/rest/reference/pulls#get-a-pull-request"
}
Error:
Could not find pull request information,
if you are using a private repo then perhaps
Danger does not have permission to access that repo.

Uncaught Kotlin exception: kotlin.Exception: Command $(which danger) ci --process danger-kotlin --passURLForDSL --failOnErrors --no-publish-check exited with code 256
at 0 danger-kotlin 0x418785 kfun:systems.danger.cmd.Cmd.exec#internal + 1221
at 1 danger-kotlin 0x419fd8 kfun:systems.danger.cmd.dangerjs.DangerJS#process(systems.danger.cmd.Command;kotlin.String;kotlin.collections.List){} + [13](https://github.com///actions/runs//jobs/#step:4:14)36
at 2 danger-kotlin 0x4170c6 kfun:#main(kotlin.Array){} + 1734
at 3 danger-kotlin 0x4231a3 Init_and_run_start + 1811
at 4 danger-kotlin 0x4232da main + 10
at 5 libc.so.6 0x7fadb04e5d8f 0x0 + [14](https://github.com///actions/runs//jobs/#step:4:15)0383963995535
at 6 libc.so.6 0x7fadb04e5e3f __libc_start_main + 127
at 7 danger-kotlin 0x405080 0x0 + 4[21](https://github.com///actions/runs//jobs/#step:4:22)4912
```

Here is how I'm using it in my workflow:

```
- name: Danger
uses: docker://ghcr.io/danger/danger-kotlin:1.2.0
with:
args: --failOnErrors --no-publish-check
env:
GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
```

Start by reproducing the Docker-based GitHub Actions invocation shown in the issue, using the danger-kotlin 1.2.0 image and the `danger ci --process danger-kotlin` command. Inspect how the command obtains pull request information and handles the displayed GitHub API 403; done means private-repository pull request data is retrieved or the failure clearly identifies the required permission.

Written by the indexing model from the issue text.