[Iamrodos]

Fixes #532.

Reading /repos/{owner}/{repo}/hooks needs admin access, and GitHub returns 404 rather than 403 without it. An empty hooks list returns 200 []. #238 (for #176) assumed the 404 meant "no hooks" and turned the crash into a skip, but make_request_with_retry still logs API Error: 404 Not Found at ERROR first. That happens for every repository the token doesn't administer, such as starred repositories with --all-starred.

This PR makes the following changes:

• When the repository listing reports permissions.admin: false, hooks are skipped without making the request. If the field is missing, the request goes ahead as before.
• The 404 skip message now names the repository and the access it needs (admin, or Webhooks read for fine-grained tokens).
• The README note "Starred public repo hooks blocking" no longer applied, since the backup carries on. It's replaced with a short note on the admin requirement.

Testing

• tests/test_hooks.py covers:
  • non-admin: no request is made
  • admin, and the permissions field missing: the request is made
  • 404: skipped with the reason
  • other errors still propagate
• pytest: 179 passed. flake8 with CI's flags and rst-lint README.rst pass.
• Real runs, master vs this branch:
  • Public repos plus 23 starred repos with --all-starred --hooks: master logged 22 API Error: 404 lines and left 22 empty hooks/ folders. This branch made no hooks requests to the non-admin repos and logged no errors. The 5 hooks.json files for owned repos are byte-identical.
  • --all --private on one repo, and --private --issues --labels --milestones --releases --hooks across 25 repos: identical output and logs.