fix(package.json): move codecov to devDependencies

Author: jedwards1211

package.json

@@ -66,6 +66,7 @@
     "babel-register": "^6.23.0",
     "babel-runtime": "^6.23.0",
     "chai": "^3.5.0",
+    "codecov": "^2.3.0",
     "copy": "^0.3.0",
     "eslint": "^3.15.0",
     "eslint-plugin-flowtype": "^2.30.0",
@@ -80,7 +81,4 @@
     "semantic-release": "^6.3.6",
     "validate-commit-msg": "^2.11.1"
   },
-  "dependencies": {
-    "codecov": "^2.3.0"
-  }
 }