github: split nu where in needs-more-info timer

GitHub's /issues/:n/events endpoint returns a mixed-schema table.
Only labeled/unlabeled rows carry a `label` column. Nu's `where`
does not short-circuit on missing columns, so the combined
predicate `event == "labeled" and label.name == ...` dereferenced
`label.name` on every row and crashed on the first non-labeled
event with `nu::shell::column_not_found`.

The scheduled job has failed every night since 2026-04-13 (the
first run with a labeled issue), so no `needs-more-info` issue
has been auto-closed.

Split into two sequential `where` filters so `label.name` is only
accessed on rows that have the column.

.github/workflows/needs-more-info-timer.yml

@@ -60,7 +60,8 @@ jobs:
             let events = (gh api $"repos/($env.GH_REPO)/issues/($number)/events"
               --paginate | from json | flatten)
             let label_event = ($events
-              | where event == "labeled" and label.name == "needs-more-info"
+              | where event == "labeled"
+              | where label.name == "needs-more-info"
               | last)
             let label_added_at = ($label_event.created_at | into datetime)