Update actions/cache action to v4

Author: renovate[bot]

.github/workflows/main.yml

@@ -17,7 +17,7 @@ jobs:
       - name: Init submodules
         run: git submodule update --init --recursive
 
-      - uses: actions/cache@v3
+      - uses: actions/cache@v4
         with:
           path: /tmp/hugo_cache
           key: ${{ runner.os }}-hugomod-${{ hashFiles('**/go.sum') }}

.github/workflows/test.yml

@@ -21,7 +21,7 @@ jobs:
       - name: Init submodules
         run: git submodule update --init --recursive
 
-      - uses: actions/cache@v3
+      - uses: actions/cache@v4
         with:
           path: /tmp/hugo_cache
           key: ${{ runner.os }}-hugomod-${{ hashFiles('**/go.sum') }}