add cache to workflows using actions/setup-node

Author: oscard0m

.github/workflows/tox.yml

@@ -81,9 +81,10 @@ jobs:
         python-version: 3.7
     - name: Setup Node
       if: ${{ matrix.tox-env == 'checklinks' }}
-      uses: actions/setup-node@v1
+      uses: actions/setup-node@v2
       with:
         node-version: '10'
+        cache: npm
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip tox