chore(package): update mocha to version 7.1.0

Closes #2

Author: greenkeeper[bot]

package.json

@@ -29,7 +29,7 @@
   "homepage": "https://github.com/mnkhouri/node-gbfs-client#readme",
   "devDependencies": {
     "@types/node": "^8.0.17",
-    "mocha": "^3.4.2",
+    "mocha": "^7.1.0",
     "nyc": "^11.0.3",
     "tslint": "^5.6.0",
     "typescript": "^2.4.2"