github: drop nu flatten in needs-more-info timer

The scheduled job has failed every night since 2026-04-13. Two
prior fixes (race-condition guards and splitting the combined
where predicate in #3200) did not address the actual cause:
`flatten` collapses nested records in a list-of-records pipeline,
so after `gh api ... | from json | flatten` the `label` and `user`
columns no longer exist - their fields are lifted to the top
level (with prefix only on naming collisions). `where label.name
== ...` and `where user.type != "Bot"` then both reference a
column that is not there.

`gh api --paginate` already returns a single concatenated JSON
array, so `from json` produces a list of records directly and no
flattening is needed. Drop both `| flatten` calls.

Verified locally with nu 0.108 against the events stream of issue
#3178: without flatten, `where event == "labeled" | where
label.name == "needs-more-info" | last` returns the labeled event
with its `label` record intact.

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

@@ -58,7 +58,7 @@ jobs:
 
             # Find when needs-more-info was last added
             let events = (gh api $"repos/($env.GH_REPO)/issues/($number)/events"
-              --paginate | from json | flatten)
+              --paginate | from json)
             let label_event = ($events
               | where event == "labeled"
               | where label.name == "needs-more-info"
@@ -67,7 +67,7 @@ jobs:
 
             # Check for non-bot comments after the label was added
             let comments = (gh api $"repos/($env.GH_REPO)/issues/($number)/comments"
-              --paginate | from json | flatten)
+              --paginate | from json)
             let human_responses = ($comments
               | where user.type != "Bot"
               | where { ($in.created_at | into datetime) > $label_added_at })