Another old checkout action

Author: markstory

.github/workflows/doc.yml

@@ -25,7 +25,7 @@ jobs:
     if: github.repository_owner == 'markstory'
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - name: Install Python dependencies
         run: |
           pip install -r requirements.txt