chore(package): update @babel/preset-env to version 7.3.1

Closes #139

Author: greenkeeper[bot]

package.json

@@ -37,7 +37,7 @@
   },
   "devDependencies": {
     "@babel/core": "7.3.3",
-    "@babel/preset-env": "7.2.3",
+    "@babel/preset-env": "7.3.1",
     "del": "3.0.0",
     "eslint": "5.11.0",
     "eslint-config-google": "0.11.0",