Update dependency supertest to v3.4.0

Author: renovate-bot

package.json

@@ -97,6 +97,6 @@
     "nyc": "13.0.1",
     "pm2": "3.1.2",
     "sequelize-cli": "4.1.1",
-    "supertest": "3.3.0"
+    "supertest": "3.4.0"
   }
 }