Bump actions/checkout from 3 to 4

Author: MagicLike

.github/workflows/docs-deploy.yml

@@ -17,7 +17,7 @@ jobs:
   deploy:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
         with:
           fetch-depth: '0'
       - uses: actions/setup-python@v4