Intermittent failures with githubPullsIssues 403

Sometimes Thanos docs CI fails with,
```
error: fmt command failed: parsing githubPullsIssues Regex: pulls API request failed. status code: 403
```
Usually,  running it again fixes it, but looks like some sort of GH API status code change.

example run: https://github.com/thanos-io/thanos/actions/runs/4075303620/jobs/7021527328