ci: 👷 add nextjs cache

.github/workflows/nodejs.yml

@@ -18,6 +18,11 @@ jobs:
         uses: actions/setup-node@v1
         with:
           node-version: '14'
+      - name: Use NextJS Cache
+        uses: actions/cache@v2
+        with:
+          path: ${{ github.workspace }}/.next/cache
+          key: ${{ runner.os }}-nextjs-${{ hashFiles('**/package-lock.json') }}
       - name: Install deps
         run: npm ci
       - name: Test and build