chore(package): update mocha to version 5.2.0

Closes #246

Author: greenkeeper[bot]

package.json

@@ -69,7 +69,7 @@
     "karma-webpack": "^2.0.4",
     "lint-staged": "^6.0.0",
     "material-components-web": "^0.24.0",
-    "mocha": "^3.5.3",
+    "mocha": "^5.2.0",
     "mocha-css": "^1.0.1",
     "node-sass": "^4.5.3",
     "null-loader": "^0.1.1",