Add dependency caching

.github/workflows/pr.yaml

@@ -9,17 +9,34 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v2
+
       - uses: actions/setup-node@v2
         with:
           node-version: 'lts/*'
           cache: 'npm'
-      - run: npm install
+
+      - name: Cache Node modules
+        uses: actions/cache@v2
+        env:
+          cache-name: cache-node-modules
+        with:
+          # npm cache files are stored in `~/.npm` on Linux/macOS
+          path: ~/.npm
+          key: ${{ runner.os }}-build-${{ env.cache-name }}-${{ hashFiles('**/package-lock.json') }}
+          restore-keys: |
+            ${{ runner.os }}-build-${{ env.cache-name }}-
+            ${{ runner.os }}-build-
+            ${{ runner.os }}-
+
+      - name: "Install dependencies"
+        run: |
+          npm install
+          sudo npx playwright install-deps
 
       - name: Lint
         run: npm run lint
       - name: Test Node
         run: npm run test-node
       - name: Test browsers
         run: |
-          sudo npx playwright install-deps
           npm run test-browser