ci(workflow): add cache to workflows using actions/setup-node (#9757)

* ci(workflow): add 'npm' cache for actions/setup-node in .github/workflows

* style(workflows): restore single quotes and remove unnecessary 'null'

.github/workflows/deploy-docs.yml

@@ -10,27 +10,28 @@ jobs:
   correct_repository:
     runs-on: ubuntu-latest
     steps:
-    - name: fail on fork
-      if: github.repository_owner != 'chartjs'
-      run: exit 1
+      - name: fail on fork
+        if: github.repository_owner != 'chartjs'
+        run: exit 1
 
   build:
     needs: correct_repository
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v2
-    - name: Use Node.js
-      uses: actions/setup-node@v1
-      with:
-        node-version: '14.x'
-    - name: Package & Deploy Docs
-      run: |
-        npm ci
-        npm run build
-        ./scripts/docs-config.sh "master"
-        npm run docs
-        npm pack
-        ./scripts/deploy-docs.sh "master"
-      env:
-        GITHUB_TOKEN: ${{ secrets.GH_AUTH_TOKEN }}
-        GH_AUTH_EMAIL: ${{ secrets.GH_AUTH_EMAIL }}
+      - uses: actions/checkout@v2
+      - name: Use Node.js
+        uses: actions/setup-node@v2
+        with:
+          node-version: '14.x'
+          cache: npm
+      - name: Package & Deploy Docs
+        run: |
+          npm ci
+          npm run build
+          ./scripts/docs-config.sh "master"
+          npm run docs
+          npm pack
+          ./scripts/deploy-docs.sh "master"
+        env:
+          GITHUB_TOKEN: ${{ secrets.GH_AUTH_TOKEN }}
+          GH_AUTH_EMAIL: ${{ secrets.GH_AUTH_EMAIL }}