chore(package): update mocha to version 6.1.2

Author: greenkeeper[bot]

package.json

@@ -41,7 +41,7 @@
   },
   "devDependencies": {
     "chai": "^4.2.0",
-    "mocha": "^6.0.0"
+    "mocha": "^6.1.2"
   },
   "bugs": {
     "url": "https://github.com/tideflow-io/tideflow-agent/issues"