chore(package): update mocha to version 6.1.1

Closes #16

Author: greenkeeper[bot]

package.json

@@ -27,7 +27,7 @@
     "express-bunyan-logger": "^1.3.2"
   },
   "devDependencies": {
-    "mocha": "^5.0.0",
+    "mocha": "^6.1.1",
     "supertest": "^3.0.0"
   }
 }