chore(package): update mocha to version 6.0.0 (#132)

Author: greenkeeper[bot]

package.json

@@ -58,7 +58,7 @@
     "gulp-sass": "^4.0.1",
     "gulp-scss-lint": "^1.0.0",
     "jsdom": "^13.1.0",
-    "mocha": "^5.0.5",
+    "mocha": "^6.0.0",
     "react": "^16.0.0",
     "react-dom": "^16.0.0",
     "react-test-renderer": "^16.0.0",