build: support Node.js 16.x

Author: dougwilson

.github/workflows/ci.yml

@@ -96,6 +96,9 @@ jobs:
  - name: Node.js 15.x
  node-version: "15.14"
 
+ - name: Node.js 16.x
+ node-version: "16.13"
+
  steps:
  - uses: actions/checkout@v2