chore: add missing trailing newline in actionlint workflow

yamllint on this PR fails on the master state of
.github/workflows/actionlint.yml with new-line-at-end-of-file. Adding
the trailing newline unblocks CI on this branch.

Author: davvd

.github/workflows/actionlint.yml

@@ -16,4 +16,4 @@ jobs:
     runs-on: ubuntu-24.04
     steps:
       - uses: actions/checkout@v6
-      - uses: reviewdog/action-actionlint@v1.72.0
+      - uses: reviewdog/action-actionlint@v1.72.0