Update actions/cache action to v4

Author: renovate[bot]

.github/workflows/continuous-integration.yml

@@ -16,7 +16,7 @@ jobs:
 
       - uses: actions/checkout@v2
 
-      - uses: actions/cache@v2
+      - uses: actions/cache@v4
         with:
           path: ~/.npm
           key: ${{ runner.os }}-node-${{ hashFiles('**/package-lock.json') }}
@@ -46,7 +46,7 @@ jobs:
 
       - uses: actions/checkout@v2
 
-      - uses: actions/cache@v2
+      - uses: actions/cache@v4
         with:
           path: ~/.npm
           key: ${{ runner.os }}-node-${{ hashFiles('**/package-lock.json') }}