chore(package): update mocha to version 6.1.2

Closes #109

Author: greenkeeper[bot]

package.json

@@ -57,7 +57,7 @@
     "gulp": "^3.9.1",
     "gulp-babel": "^7.0.0",
     "gulp-eslint": "^4.0.0",
-    "mocha": "^3.4.2",
+    "mocha": "^6.1.2",
     "pg-native": "^2.0.1"
   }
 }