Update actions/cache action to v6 (#311)

Author: renovate[bot]

.github/workflows/build.yml

@@ -290,7 +290,7 @@ jobs:
           jq . infection.json5
 
       - name: "Restore result cache"
-        uses: actions/cache/restore@caa296126883cff596d87d8935842f9db880ef25 # v5.1.0
+        uses: actions/cache/restore@55cc8345863c7cc4c66a329aec7e433d2d1c52a9 # v6.1.0
         with:
           path: ./tmp
           key: "result-cache-v1-${{ matrix.php-version }}-${{ github.run_id }}"
@@ -311,7 +311,7 @@ jobs:
             --logger-text=php://stdout
 
       - name: "Save result cache"
-        uses: actions/cache/save@caa296126883cff596d87d8935842f9db880ef25 # v5.1.0
+        uses: actions/cache/save@55cc8345863c7cc4c66a329aec7e433d2d1c52a9 # v6.1.0
         if: ${{ !cancelled() }}
         with:
           path: ./tmp