chore(package): update mocha to version 6.2.0

Closes #16

Author: greenkeeper[bot]

package.json

@@ -43,7 +43,7 @@
         "coveralls": "^3.0.2",
         "istanbul": "^0.4.5",
         "log4bro": "^3.7.1",
-        "mocha": "^5.2.0",
+        "mocha": "^6.2.0",
         "mocha-lcov-reporter": "^1.3.0",
         "testdouble": "^3.8.1",
         "uuid": "^3.3.2"