chore(package): update mocha to version 6.1.3

Closes #123

Author: greenkeeper[bot]

package.json

@@ -41,7 +41,7 @@
     "guide4you-proxy": "github:KlausBenndorf/guide4you-proxy#v1.1.0",
     "http-server": "0.11.1",
     "jquery": "3.3.1",
-    "mocha": "5.2.0",
+    "mocha": "6.1.3",
     "ol": "5.2.0",
     "phantomjs-prebuilt": "2.1.14",
     "selenium-webdriver": "^3.6.0",