chore: add node 16 to ci.yaml (GoogleCloudPlatform#189)

Author: nimf

.github/workflows/ci.yaml

@@ -8,7 +8,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        node: [10, 12, 14]
+        node: [10, 12, 14, 16]
     steps:
       - uses: actions/checkout@v3
       - uses: actions/setup-node@v3