Bump cross-env from 6.0.3 to 7.0.2

Bumps [cross-env](https://github.com/kentcdodds/cross-env) from 6.0.3 to 7.0.2.
- [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...v7.0.2)

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

package.json

@@ -37,7 +37,7 @@
   "devDependencies": {
     "ava": "^3.13.0",
     "coveralls": "^3.0.6",
-    "cross-env": "^6.0.3",
+    "cross-env": "^7.0.2",
     "eslint": "^5.3.0",
     "eslint-config-airbnb": "^17.1.1",
     "eslint-plugin-import": "^2.18.2",