chore(package): update @babel/core to version 7.9.0

Closes #1502

Author: greenkeeper[bot]

package.json

@@ -73,7 +73,7 @@
     "semver": "7.1.3"
   },
   "devDependencies": {
-    "@babel/core": "7.8.7",
+    "@babel/core": "7.9.0",
     "@babel/plugin-proposal-decorators": "7.8.3",
     "@babel/plugin-transform-regenerator": "7.8.7",
     "@babel/plugin-transform-runtime": "7.8.3",