fix version import

[wiese-m]

Summary

Fixed version import in playtest.py & added missing return type in version()

Closes #586
Closes #582

[joe-clickhouse]

Thanks @wiese-m. Appreciate the PR. See my comment below about common. As for the return type, that's a good call. Though there are some other functions in common that could benefit from return types as well. So if you're up for it, I'd suggest adding correct return types to the rest of the functions in common if they're missing them!

I also recently found a default/typing-related bug tracked in #586. All that's required there is changing the type of executor_threads parameter in create_async_client from Optional[int] to just a plain int and then change the default value from None to 0.

I see you've opened #582 as well (thanks!). So if you wouldn't mind, I suggest combing all this into a single PR that:

1. Adds return types to all the functions missing them in common.py
2. Fixes the default value and type of executor_threads from #586
3. Fixes the test path you issue you found in #582
4. Reverts the version import in palaytest.py and uses the public entry point of clickhosue_connect.version()

Let me know if you have any questions and thanks again!

[wiese-m]

Thanks for answer & suggestions. I pushed all the necessary changes.

[joe-clickhouse]

Looks good! Thanks for the help.