Cache dependencies

.github/workflows/main.yml

@@ -6,6 +6,12 @@ jobs:
     steps:
       - name: Checkout
         uses: actions/checkout@v2
+      - uses: actions/cache@v2
+        with:
+          path: ~/.npm
+          key: ${{ runner.os }}-node-${{ hashFiles('**/package-lock.json') }}
+          restore-keys: |
+            ${{ runner.os }}-node-
       - name: Install dependencies
         run: npm ci
       - name: Lint