update to actions/checkout@v4

Author: TimidRobot

.github/workflows/checks.yml

@@ -20,7 +20,7 @@ jobs:
 
     # https://github.com/actions/checkout
     - name: Checkout cc-legal-tools-app
-      uses: actions/checkout@v3
+      uses: actions/checkout@v4
 
     - name: Check published files for invalid template
       run: |