chore(package): update codecov to version 3.6.4

Closes #98

Author: greenkeeper[bot]

package.json

@@ -12,7 +12,7 @@
     "test": "test"
   },
   "devDependencies": {
-    "codecov": "3.5.0",
+    "codecov": "3.6.4",
     "commitizen": "^3.1.1",
     "concurrently": "^4.0.1",
     "cz-conventional-changelog": "^2.1.0",