build: reenable Node 15 and 16 for CI (#949)

Author: ahnpnl

.github/workflows/nodejs.yml

@@ -52,7 +52,7 @@ jobs:
       - uses: actions/checkout@v2
       - uses: actions/[email protected]
         with:
-          node-version: 12.x
+          node-version: 14.x
       - name: Get yarn cache
         id: yarn-cache
         run: echo "::set-output name=dir::$(yarn config get cacheFolder)"
@@ -74,7 +74,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        node-version: [12.x, 14.x]
+        node-version: [12.x, 14.x, 15.x, 16.x]
         os: [ubuntu-latest, windows-latest]
     runs-on: ${{ matrix.os }}
     needs: prepare-yarn-cache