chore(package): update mocha to version 6.0.2

Closes #30

Author: greenkeeper[bot]

package.json

@@ -41,7 +41,7 @@
     "loopback-boot": "2.25.0",
     "loopback-connector-mongodb": "3.2.0",
     "loopback-testing": "1.4.0",
-    "mocha": "3.4.2",
+    "mocha": "6.0.2",
     "mocha-sinon": "2.0.0",
     "nyc": "11.0.3",
     "semantic-release": "6.3.6",