The line `'unalias ORBIT_PATH &>/dev/null'` inside `setup_conda_env()`
prevents `orbit.sh --conda` to successfully exit. The "`unset`" command
rather than "`unalias`" should be used for environment variables (e.g.,
`ORBIT_PATH`). This is a problem, e.g., when a custom dockerfile is used
to directly install conda during the image build process: the image
build process is interrupted.

Fixes #377

- Bug fix (non-breaking change which fixes an issue)

Before:

https://github.com/NVIDIA-Omniverse/orbit/blob/a642b8e32cf07efa11a583e8db3680d971922e1e/orbit.sh#L148
After:
`'unset ORBIT_PATH' \`

- [x] I have run the [`pre-commit` checks](https://pre-commit.com/) with
`./orbit.sh --format`
- [ ] I have made corresponding changes to the documentation
- [x] My changes generate no new warnings
- [ ] I have added tests that prove my fix is effective or that my
feature works
- [ ] I have run all the tests with `./orbit.sh --test` and they pass
- [ ] I have updated the changelog and the corresponding version in the
extension's `config/extension.toml` file
- [x] I have added my name to the `CONTRIBUTORS.md` or my name already
exists there