Fix for Github clone on Windows

[WWM-jschuba]

The GitHubRepository.get_directory() method did not work on Windows, because the slashes in the temp path were being removed by shlex. The fix is to wrap the path with "quotes". This is the proposed fix in the issue 13180 discussion.

closes #13180

Checklist

• This pull request references any related issue by including "closes <link to issue>"

[zzstoatzz]

thank you for the PR! looks like we need pre-commit run --all-files here to pass CI

[WWM-jschuba]

I read and ran the existing tests here. The core functionality of the Github clone command is untested. The tests all mock this away.

The functionality of GithubRepository.get_directory() is

1. Receive references for (or create) two temp directories (content_source, content_destination) -> mocked by tests
2. Clone the target Github Repo into content_source -> Silently fails because of test mocks.
3. Copy contents of content_source into content_destination -> works, and is tested

Because the content_source temp directory is already created in the test mocks, with files inside, the clone command in step 2 fails silently (you cannot git clone into a non-empty directory). This may have been the intention of the test writer, so the tests would not download the large prefect.git repo.

However, only steps 1 and 3 are actually tested now, and the core purpose of the function, cloning a repo, is untested.

That is why the tests pass on Windows, but the module doesn't work in practice. Wrapping the path in quotes very straightforwardly fixes the issue for all OS's.

[cicdw]

LGTM