gh-36894: Adjust the sync label bot to reflect recent GitHub CLI changes
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At least since version 2.40.0 of `gh` the output of `gh auth status` has
changed. This broke the method `bot_login` where the bot's login name is
obtained. The first failure appeared on 13.12 in [this scheduled run](ht
tps://github.com/sagemath/sage/actions/runs/7199213174/job/19610401946).
More specifically, the word before the login name used for positioning
has changed from `as` to `account`.
In a logfile it looks like this:
```
Run chmod a+x .github/sync_labels.py
INFO:root:cmdline_args (1) ['https://github.com/sagemath/sage']
INFO:root:url: https://github.com/sagemath/sage
INFO:root:Create label handler for pull request #sage and actor
sagetrac-github-bot
Traceback (most recent call last):
File "/home/runner/work/sage/sage/.github/sync_labels.py", line 1081,
in <module>
gh = GhLabelSynchronizer(url, default_actor)
File "/home/runner/work/sage/sage/.github/sync_labels.py", line 157,
in __init__
self.bot_login()
File "/home/runner/work/sage/sage/.github/sync_labels.py", line 244,
in bot_login
self._bot_login = l[l.index('as')+1]
ValueError: 'as' is not in list
Error: Process completed with exit code 1.
```
This PR does the following:
* implements an adjustment to this change
* avoids raising an error if the bot name cannot be discovered (to
better behave with similar changes in the future)
* adds more log messages to make it easier to identify similar issues
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URL: https://github.com/sagemath/sage/pull/36894
Reported by: Sebastian Oehms
Reviewer(s): Kwankyu Lee
