Merge pull request #18 from yourtion/greenkeeper/supertest-4.0.0

Update supertest to the latest version 🚀

Author: yourtion

package.json

@@ -35,7 +35,7 @@
     "express": "^4.16.2",
     "istanbul": "^0.4.5",
     "mocha": "^5.0.0",
-    "supertest": "^3.0.0"
+    "supertest": "^4.0.0"
   },
   "dependencies": {
     "lei-coroutine": "^1.6.3"