Bump cross-env from 6.0.3 to 7.0.0 (#30094)

Bumps [cross-env](https://github.com/kentcdodds/cross-env) from 6.0.3 to 7.0.0.
- [Release notes](https://github.com/kentcdodds/cross-env/releases)
- [Changelog](https://github.com/kentcdodds/cross-env/blob/master/CHANGELOG.md)
- [Commits](kentcdodds/cross-env@v6.0.3...v7.0.0)

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

package.json

@@ -102,7 +102,7 @@
     "babel-plugin-istanbul": "^6.0.0",
     "bundlesize": "^0.18.0",
     "clean-css-cli": "^4.3.0",
-    "cross-env": "^6.0.3",
+    "cross-env": "^7.0.0",
     "eslint": "^6.8.0",
     "eslint-config-xo": "^0.27.2",
     "eslint-plugin-import": "^2.20.0",