feat: default github-token to github.token

[robbertbos]

Description

The github-token input now defaults to ${{ github.token }}, so users no longer need to explicitly pass github-token: ${{ secrets.GITHUB_TOKEN }}.

This follows the same pattern as GitHub's official actions/checkout action.

Before:

comment-on-pr: true
github-token: ${{ secrets.GITHUB_TOKEN }}

After:

comment-on-pr: true

A custom token is only needed for cross-repository operations or when using a PAT.

Note: Users still need to set permissions at workflow level (e.g., pull-requests: write).

Type of Change

• Bug fix
• New feature
• Breaking change (changes to action inputs/outputs)
• Documentation update

Checklist

• I have tested these changes locally
• I have updated the documentation (if applicable)
• My changes follow the existing code style
• I have added/updated comments where necessary

Testing

• Verified syntax matches GitHub's actions/checkout pattern
• Validated action.yml files are valid YAML

Breaking Changes

None. Fully backwards compatible - existing workflows that explicitly pass github-token will continue to work.

References

• GitHub Docs: Automatic token authentication
• actions/checkout action.yml - uses same pattern