prevent node 16 from being installed in heroku

Author: mansona

package.json

@@ -106,7 +106,7 @@
     "testem": "^2.14.0"
   },
   "engines": {
-    "node": "10.* || >= 12",
+    "node": "10.* || 12.* || 14.*",
     "npm": "7",
     "yarn": "1.22.10"
   },