Update dependency mocha to v6

package.json

@@ -24,7 +24,7 @@
     "chai": "4.2.0",
     "jsdoc": "3.5.5",
     "minami": "1.2.3",
-    "mocha": "5.2.0",
+    "mocha": "6.0.1",
     "nodemon": "1.18.10"
   },
   "dependencies": {