Turn on lint for PR and master

.github/workflows/lint.yml

@@ -10,10 +10,16 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v1
+
+      - uses: actions/cache@v2
+        with:
+          path: '**/node_modules'
+          key: ${{ runner.os }}-modules-${{ hashFiles('**/yarn.lock') }}
+
       - name: Install modules
-        run: yarn
+        run: yarn install
         working-directory: ./js
+
       - name: Run ESLint
         run: yarn lint:eslint
         working-directory: ./js
-