ci: Fix bump-api-schema workflow to merge PRs immediately (#16827)

## DESCRIBE YOUR PR

The `bump-api-schema-sha.yml` workflow creates PRs with `--auto` merge,
but checks never pass — causing a pile-up of open "Bump API schema" PRs.
Since getsentry bot has been added to bypass PR requirements, we can use
`--admin` to merge immediately.

Changes:
- Add no-op guard after `sed` to skip when the SHA is unchanged
(prevents duplicate PRs)
- Switch `gh pr merge --squash --auto` → `gh pr merge --squash --admin`
(bypass branch protections, merge immediately)

## IS YOUR CHANGE URGENT?

- [ ] Urgent deadline (GA date, etc.):
- [ ] Other deadline:
- [x] None: Not urgent, can wait up to 1 week+

## SLA

- Teamwork makes the dream work, so please add a reviewer to your PRs.
- Please give the docs team up to 1 week to review your PR unless you've
added an urgent due date to it.
Thanks in advance for your help!

## PRE-MERGE CHECKLIST

- [x] Checked Vercel preview for correctness, including links
- [ ] PR was reviewed and approved by any necessary SMEs (subject matter
experts)
- [ ] PR was reviewed and approved by a member of the [Sentry docs
team](https://github.com/orgs/getsentry/teams/docs)

Co-authored-by: Claude <noreply@anthropic.com>

Author: sergical

.github/workflows/bump-api-schema-sha.yml

@@ -39,11 +39,16 @@ jobs:
           sed -i -e "s|^const SENTRY_API_SCHEMA_SHA =.*$|const SENTRY_API_SCHEMA_SHA = '$sha';|g" "$filepath"
           echo "Updated $filepath"
 
+          if git diff --quiet "$filepath"; then
+            echo "No changes to $filepath, skipping."
+            exit 0
+          fi
+
           branch="bot/bump-api-schema-to-${sha:0:8}"
           git checkout -b "$branch"
           git add "$filepath"
           git commit -m "Bump API schema to ${sha:0:8}"
           git push --set-upstream origin "$branch"
 
           gh pr create --fill
-          gh pr merge --squash --auto
+          gh pr merge --squash --admin