cicd: update checkout action version

Author: jsstevenson

.github/workflows/checks.yaml

@@ -5,7 +5,7 @@ jobs:
     name: test python
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
 
       - name: Setup Python
         uses: actions/setup-python@v5