Update actions/checkout action to v4

Author: renovate[bot]

.github/workflows/layers_dispatch.yaml

@@ -17,7 +17,7 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v2
+        uses: actions/checkout@v4
 
       - name: Setup AWS CLI
         uses: aws-actions/configure-aws-credentials@v1

.github/workflows/update_readme.yaml

@@ -18,7 +18,7 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v2
+        uses: actions/checkout@v4
 
       - name: Setup AWS CLI
         uses: aws-actions/configure-aws-credentials@v1