Merge pull request jsonwebtoken#646 from jsonwebtoken/defineNode

Define explicitly node version 16 to be able to migrate to heroku 22 stack

Author: monikakinder

package.json

@@ -71,6 +71,9 @@
         "webpack-merge": "^4.2.1",
         "xhr-mock": "^2.4.1"
     },
+    "engines": {
+        "node": "16"
+    },
     "scripts": {
         "start": "node server.js",
         "test": "grunt test",