Chore: upgrade devDependencies

Author: mysticatea

package.json

@@ -17,7 +17,7 @@
   },
   "devDependencies": {
     "chokidar-cli": "^1.2.0",
-    "codecov": "^2.3.0",
+    "codecov": "^3.0.0",
     "eslint": "^4.7.0",
     "eslint-config-mysticatea": "^12.0.0",
     "mocha": "^4.0.0",