Update actions/cache action to v4

.github/workflows/ci.yml

@@ -13,15 +13,15 @@ jobs:
       uses: docker/setup-buildx-action@v1
 
     - name: Cache Docker layers
-      uses: actions/cache@v2
+      uses: actions/cache@v4
       with:
         path: /tmp/.buildx-cache
         key: ${{ runner.os }}-buildx-${{ github.sha }}
         restore-keys: |
           ${{ runner.os }}-buildx-
 
     - name: Cache make init results
-      uses: actions/cache@v2
+      uses: actions/cache@v4
       with:
         path: |
           webapp/sql/dump.sql