[Bugfix] Add github_token verification in resolver utils

[tawago]

• This change is worth documenting at https://docs.all-hands.dev/
• Include this change in the Release Notes. If checked, you must provide an end-user friendly description for your change below

End-user friendly description of the problem this fixes or functionality that this introduces.
Previously, users would encounter a "Token is invalid" error when using the default GITHUB_TOKEN in GitHub Actions workflows, requiring them to set up a Personal Access Token (PAT) instead. With this fix, the resolver correctly validates GitHub Actions tokens, allowing workflows to run without additional token setup.

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Give a summary of what the PR does, explaining any non-trivial design decisions.
The PR modifies the identify_token function to properly validate GitHub Actions tokens by:

• Adding support for the Bearer authentication format used by GitHub Actions tokens
• Using the repository endpoint instead of the user endpoint for validation, as GitHub Actions tokens have repository-scoped permissions
• Accepting an optional repository parameter to use for validation
• Maintaining backward compatibility with existing PAT validation logic

This approach ensures that both GitHub Actions tokens and Personal Access Tokens can be validated correctly, providing a seamless experience for users in both GitHub Actions workflows and other environments.

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Link of any specific issues this addresses.
I believe the bug was introduced in #6458

[malhotra5]

LGTM, thanks a bunch for this catch!

[malhotra5]

Hi @tawago, thanks a bunch for the contributions! I've approved the workflows here, please update the code until they are all passing so we can get this merged 🙂

[tawago]

Let me confirm some cases on my local before merging this. I will update asap

[tawago]

@malhotra5
Okay, tested a workflow on my forked repository: https://github.com/tawago/OpenHands/actions/runs/13623744851/job/38077431478
This PR should work as expected and all checks seems passing