Update mocha to the latest version 🚀 (#30)

Author: greenkeeper[bot]

packages/google-cloud-language/package.json

@@ -74,7 +74,7 @@
     "ink-docstrap": "^1.3.0",
     "intelli-espower-loader": "^1.0.1",
     "jsdoc": "^3.5.5",
-    "mocha": "^4.0.1",
+    "mocha": "^5.0.0",
     "nyc": "^11.2.1",
     "power-assert": "^1.4.4",
     "prettier": "^1.7.4"