fix(package): update mocha to version 7.1.1

Closes #17

Author: greenkeeper[bot]

package.json

@@ -10,7 +10,7 @@
   "license": "ISC",
   "dependencies": {
     "chai": "^4.1.2",
-    "mocha": "^6.0.0",
+    "mocha": "^7.1.1",
     "botkit": "^4.5.0",
     "forecast.io": "0.0.11",
     "slackbots": "^1.1.0"