This PR fixes the PR release workflow which was failing due to the
deprecated `MATHLIB4_COMMENT_BOT` PAT being invalid.
**Error:** `jq: error (at <stdin>:4): Cannot index string with string
"name"` when fetching labels - the API returned an error response
instead of labels array because the PAT credentials were bad.
**Changes:**
- Generate a token from the `mathlib-lean-pr-testing` GitHub App (ID:
2785182) for posting comments to Lean PRs about mathlib compatibility
- Use `GITHUB_TOKEN` for read-only label fetching (no special identity
needed)
- Update the bot username check from `leanprover-community-bot` to
`mathlib-lean-pr-testing[bot]`
**Secrets added:** `MATHLIB_LEAN_PR_TESTING_APP_ID` and
`MATHLIB_LEAN_PR_TESTING_PRIVATE_KEY` have been added to the repository.
Fixes the CI failure at
https://github.com/leanprover/lean4/actions/runs/21705647318/job/62595966115🤖 Prepared with Claude Code
Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>
abcb57d234