Attempt to fix "copy labels from issues" workflow permissions again

It's still broken:

https://github.com/ppy/osu/actions/runs/22310482792/job/64540909415

and I'm not sure what else it could be other than this, so I'm giving it
one more honest try before I throw up hands.

For better or worse,
https://docs.github.com/en/actions/reference/workflows-and-actions/workflow-syntax#permissions
explicitly lists that the `pull-requests` permission allows tagging PRs,
so I'm holding out hope that this is it. Still terrible marks for
documentation here, both to the github action, as well as everything to
do with `GITHUB_TOKEN`.

.github/workflows/pull-request-copy-labels.yml

@@ -5,8 +5,8 @@ on:
     types: [opened]
 
 permissions:
-  issues: write # to read the labels of any linked issue(s), and to put the found labels if any on the PR
-  # not granting any `pull_requests` permissions because in github's modeling pull requests are a subset of issues. it's confusing.
+  issues: read # to read the labels of any linked issue(s)
+  pull-requests: write # to put the found labels if any on the PR
 
 jobs:
   copy-labels: