fix(package): require Node.js 8.3+

Author: mrmlnc

package.json

@@ -22,7 +22,7 @@
   ],
   "main": "index.js",
   "engines": {
-    "node": ">=8"
+    "node": ">=8.3"
   },
   "scripts": {
     "test": "mocha -r ./test/mocha-initialization.js",