chore: add node16 to CI matrix

Author: lukeed

.github/workflows/ci.yml

@@ -8,7 +8,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        nodejs: [8, 10, 12, 14]
+        nodejs: [8, 10, 12, 14, 16]
     steps:
     - uses: actions/checkout@v2
     - uses: actions/setup-node@v2