chore(deps-dev): bump @babel/core from 7.6.3 to 7.6.4

Bumps [@babel/core](https://github.com/babel/babel) from 7.6.3 to 7.6.4.
- [Release notes](https://github.com/babel/babel/releases)
- [Changelog](https://github.com/babel/babel/blob/master/CHANGELOG.md)
- [Commits](https://github.com/babel/babel/compare/v7.6.3...v7.6.4)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

package.json

@@ -16,7 +16,7 @@
     "scheduler": "^0.16.2"
   },
   "devDependencies": {
-    "@babel/core": "^7.6.3",
+    "@babel/core": "^7.6.4",
     "@babel/preset-env": "^7.6.3",
     "@babel/preset-react": "^7.6.3",
     "@types/d3": "^5.7.2",