chore(package): update np to version 6.2.2

Closes #6

Author: greenkeeper[bot]

package.json

@@ -31,7 +31,7 @@
   "devDependencies": {
     "@types/jest": "^24.0.0",
     "jest": "^24.1.0",
-    "np": "^4.0.2",
+    "np": "^6.2.2",
     "ts-jest": "^23.1.3",
     "typescript": "^3.0.1"
   },