Fixed deprecation warning for `Bundler.with_clean_env`
Fixed deprecation warning for `Bundler.with_clean_env`

```
[DEPRECATED] `Bundler.with_clean_env` has been deprecated in favor of `Bundler.with_unbundled_env`. If you instead want the environment before bundler was originally loaded, use `Bundler.with_original_env` (called at /Users/sue445/workspace/github.com/geminabox/geminabox/test/test_support/geminabox_test_case.rb:123)
```

geminabox/geminabox,geminabox/geminabox,geminabox/geminabox,geminabox/geminabox