build(deps-dev): bump @babel/preset-env from 7.5.5 to 7.6.0

Bumps [@babel/preset-env](https://github.com/babel/babel) from 7.5.5 to 7.6.0.
- [Release notes](https://github.com/babel/babel/releases)
- [Changelog](https://github.com/babel/babel/blob/master/CHANGELOG.md)
- [Commits](babel/babel@v7.5.5...v7.6.0)

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

package.json

@@ -40,7 +40,7 @@
     "@babel/core": "^7.6.0",
     "@babel/generator": "^7.6.0",
     "@babel/parser": "^7.5.0",
-    "@babel/preset-env": "^7.4.5",
+    "@babel/preset-env": "^7.6.0",
     "acorn": "^6.3.0",
     "astravel": "^0.5.0",
     "ava": "^2.3.0",