build(deps-dev): bump cross-env from 6.0.3 to 7.0.0 (#307)

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>

Author: dependabot-preview[bot]

package.json

@@ -59,7 +59,7 @@
     "@types/react": "^16.8.19",
     "@types/react-dom": "^16.8.4",
     "@types/warning": "^3.0.0",
-    "cross-env": "^6.0.0",
+    "cross-env": "^7.0.0",
     "css-animation": "^2.0.4",
     "enzyme": "^3.3.0",
     "enzyme-adapter-react-16": "^1.0.2",