KeyError: login in github_utils adding author

[navignaw]

Describe the bug revup upload fails with a python KeyError if a reviewer author is missing the "login" attribute.

I am fairly sure this is due to a review from an automated app, i.e.

as it started failing immediately after this reviewer left an automated comment on the PR.

Expected behavior revup upload works as intended

To Reproduce

1. Create a PR with an automated reviewer. One way to do so is to set up the GHA https://github.com/googleapis/code-suggester, but there are probably easier ways to automate adding a reviewer
2. Run revup upload against that topic

Logs

Traceback (most recent call last):
  File "/usr/local/bin/revup", line 8, in <module>
    sys.exit(_main())
  File "/usr/local/lib/python3.8/site-packages/revup/__main__.py", line 18, in _main
    sys.exit(asyncio.run(main()))
  File "/usr/local/Cellar/[email protected]/3.8.18/Frameworks/Python.framework/Versions/3.8/lib/python3.8/asyncio/runners.py", line 44, in run
    return loop.run_until_complete(main)
  File "/usr/local/Cellar/[email protected]/3.8.18/Frameworks/Python.framework/Versions/3.8/lib/python3.8/asyncio/base_events.py", line 616, in run_until_complete
    return future.result()
  File "/usr/local/lib/python3.8/site-packages/revup/revup.py", line 393, in main
    return await upload.main(
  File "/usr/local/lib/python3.8/site-packages/revup/upload.py", line 48, in main
    await topics.query_github()
  File "/usr/local/lib/python3.8/site-packages/revup/topic_stack.py", line 1015, in query_github
    ) = await github_utils.query_everything(
  File "/usr/local/lib/python3.8/site-packages/revup/github_utils.py", line 276, in query_everything
    reviewers.add(revs["author"]["login"])
KeyError: 'login'