chore(package): update mocha to version 7.1.1

Closes #34

Author: greenkeeper[bot]

package.json

@@ -33,7 +33,7 @@
     "ioredis": "^4.9.0",
     "istanbul": "^0.4.3",
     "safe-stable-stringify": "^1.0.0",
-    "mocha": "^6.0.0",
+    "mocha": "^7.1.1",
     "snazzy": "^8.0.0",
     "standard": "^12.0.0"
   }