chore(package): update mocha to version 6.2.1

Closes #151

Author: greenkeeper[bot]

package.json

@@ -96,7 +96,7 @@
         "gulp-typescript": "5.0.1",
         "gulp-util": "3.0.8",
         "istanbul": "0.4.5",
-        "mocha": "6.1.4",
+        "mocha": "6.2.1",
         "remap-istanbul": "0.13.0",
         "pump": "3.0.0",
         "ts-mockito": "2.3.1",