chore(package): update mocha to version 6.2.2

Closes #16

Author: greenkeeper[bot]

package.json

@@ -39,7 +39,7 @@
     "@types/express": "^4.16.2",
     "@types/express-bunyan-logger": "^1.3.1",
     "@types/mocha": "^5.0.0",
-    "mocha": "^5.0.0",
+    "mocha": "^6.2.2",
     "supertest": "^3.0.0",
     "ts-mocha": "^6.0.0",
     "tslint": "^5.18.0",