use actions/checkout@v4

v3 results in the warning "Node.js 16 actions are deprecated."

Author: mstathers

.github/workflows/deploy.yml

@@ -13,7 +13,7 @@ jobs:
     runs-on: ubuntu-22.04
 
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
 
       - name: Install Dependencies
         run: |