Bump cross-env from 5.2.1 to 6.0.3

Bumps [cross-env](https://github.com/kentcdodds/cross-env) from 5.2.1 to 6.0.3.
- [Release notes](https://github.com/kentcdodds/cross-env/releases)
- [Changelog](https://github.com/kentcdodds/cross-env/blob/master/CHANGELOG.md)
- [Commits](kentcdodds/cross-env@v5.2.1...v6.0.3)

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

package.json

@@ -46,7 +46,7 @@
     "@types/react": "^16.8.19",
     "@types/react-dom": "^16.8.4",
     "@types/warning": "^3.0.0",
-    "cross-env": "^5.2.0",
+    "cross-env": "^6.0.3",
     "enzyme": "^3.10.0",
     "enzyme-adapter-react-16": "^1.1.1",
     "enzyme-to-json": "^3.4.0",