chore(package): update supertest to version 4.0.2

Closes #38

Author: greenkeeper[bot]

package.json

@@ -55,7 +55,7 @@
     "nodemon": "^1.11.0",
     "nyc": "^11.0.0",
     "semantic-release": "^6.3.2",
-    "supertest": "^3.0.0"
+    "supertest": "^4.0.2"
   },
   "config": {
     "commitTypeMap": {