chore(package): update codecov to version 3.4.0

Closes #34

Author: greenkeeper[bot]

package.json

@@ -18,7 +18,7 @@
     "babel-jest": "^19.0.0",
     "babel-preset-es2015": "^6.24.0",
     "babel-preset-react": "^6.23.0",
-    "codecov": "^2.1.0",
+    "codecov": "^3.4.0",
     "enzyme": "^2.7.1",
     "jest": "^19.0.2",
     "lerna": "2.0.0-rc.1",