GITHUB/WORKFLOWS: change to v4

https://github.blog/changelog/2024-03-07-github-actions-all-actions-will-run-on-node20-instead-of-node16-by-default/

Author: michal-shalev

.github/workflows/auto-assign-reviewers.yml

@@ -9,7 +9,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout code
-        uses: actions/checkout@v34
+        uses: actions/checkout@v4
         with:
           fetch-depth: 0