fix(package): update ws to version 7.1.0

Closes #6

Author: greenkeeper[bot]

package.json

@@ -32,7 +32,7 @@
   },
   "homepage": "https://github.com/Block-Lab/kNight.js#readme",
   "dependencies": {
-    "ws": "^6.1.0"
+    "ws": "^7.1.0"
   },
   "devDependencies": {
     "standard": "^12.0.0",