chore(package): update mocha to version 6.1.3

Closes #32

Author: greenkeeper[bot]

package.json

@@ -56,7 +56,7 @@
     "loopback-context": "^3.1.0",
     "cls-hooked": "^4.1.5",
     "loopback-component-fixtures": "^1.1.0",
-    "mocha": "^3.4.1",
+    "mocha": "^6.1.3",
     "mocha-sinon": "latest",
     "nyc": "latest",
     "sinon": "latest",