chore(dependencies): Bump cross-env from 5.0.5 to 5.1.1 (#30)

Bumps [cross-env](https://github.com/kentcdodds/cross-env) from 5.0.5 to 5.1.1.
- [Release notes](https://github.com/kentcdodds/cross-env/releases)
- [Changelog](https://github.com/kentcdodds/cross-env/blob/master/CHANGELOG.md)
- [Commits](https://github.com/kentcdodds/cross-env/compare/v5.0.5...v5.1.1)

yarn.lock

@@ -1613,8 +1613,8 @@ create-hmac@^1.1.0, create-hmac@^1.1.2, create-hmac@^1.1.4:
     sha.js "^2.4.8"
 
 cross-env@*:
-  version "5.0.5"
-  resolved "https://registry.yarnpkg.com/cross-env/-/cross-env-5.0.5.tgz#4383d364d9660873dd185b398af3bfef5efffef3"
+  version "5.1.1"
+  resolved "https://registry.yarnpkg.com/cross-env/-/cross-env-5.1.1.tgz#b6d8ab97f304c0f71dae7277b75fe424c08dfa74"
   dependencies:
     cross-spawn "^5.1.0"
     is-windows "^1.0.0"