Actions: More cleanup

Removes the checkout action, as this is no longer needed, and folds
the `grep` into `jq`.

.github/workflows/check-change-note.yml

@@ -10,7 +10,6 @@ jobs:
   check-change-note:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
       - name: Fail if no change note found. To fix, either add one, or add the `no-change-note-required` label.
         if: |
           github.event.pull_request.draft == false &&
@@ -19,5 +18,4 @@ jobs:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
         run: |
           gh api 'repos/${{github.repository}}/pulls/${{github.event.number}}/files' --paginate |
-          jq '.[].filename' --raw-output |
-          grep '/change-notes/.*\.md$'
+          jq 'any(.[].filename ; test("/change-notes/.*[.]md$"))' --exit-status