Handle GitHub App token revoke timeouts without failing requests

[cursor]

Summary

• make GitHub App installation token revocation best-effort in GithubAppToken.get_token
• add an explicit timeout to token revocation requests to avoid hanging network calls
• catch and log revocation network errors so cleanup failures do not mask the original request flow
• add focused tests for successful revocation, revoke timeout handling, and preserving original exceptions

Root cause

Sentry issue SENTRY-GITHUB-ACTIONS-APP-6V showed ConnectTimeout raised from the finally block in token cleanup (requests.delete), which could bubble out of request handling and replace the true upstream error context. This happened when GitHub API connectivity was degraded during cleanup.

Validation

• ~/.local/bin/pytest -q tests/test_github_app.py tests/test_web_app_handler.py tests/test_sentry_config_file.py
• all tests passed (1 pre-existing skipped test)