chore(ci): run tests up to node v16

No change to logic. This adds node v15 and v16 to the CI testing.

Author: nfischer

.github/workflows/main.yml

@@ -19,6 +19,8 @@ jobs:
           - 12
           - 13
           - 14
+          - 15
+          - 16
         os:
           - ubuntu-latest
           - macos-latest

scripts/check-node-support.js

@@ -9,7 +9,7 @@ var shell = require('shelljs');
 
 // This is the authoritative list of supported node versions.
 var MIN_NODE_VERSION = 6;
-var MAX_NODE_VERSION = 14;
+var MAX_NODE_VERSION = 16;
 
 function checkReadme(minNodeVersion) {
   var start = '<!-- start minVersion -->';