chore(package): update mocha to version 7.1.2

Closes #10

Author: greenkeeper[bot]

package.json

@@ -34,7 +34,7 @@
   "devDependencies": {
     "assume": "~2.1.0",
     "istanbul": "~0.4.5",
-    "mocha": "~3.5.0",
+    "mocha": "~7.1.2",
     "pre-commit": "~1.2.0"
   }
 }