infra: publish to pypi.org using namespace package

[tcztzy]

Is your feature request related to a problem? Please describe.
Publish this project to Pypi.org using namespace package.

Describe the solution you'd like
Once it is publish as a namespace like open_webui, then third party developer can publish their package like open_webui.apps.<my_app>

Describe alternatives you've considered
No

Additional context
No

[tjbck]

Github workflow PR welcome!

[tcztzy]

I can contribute but It will rename the top level backend directory to open-webui, would you accept such a big change? And we also need a Pypi organization account.

[tjbck]

If we can rename the backend directory during our workflow that would be ideal.

[tcztzy]

it can be done without renaming the directory, but renaming the python imports is required in most cases. For example

open-webui/backend/main.py

Line 20 in 30b0531

from apps.ollama.main import app as ollama_app

should be refactored as

from open_webui.apps.ollama.main import app as ollama_app 

and

open-webui/backend/main.py

Line 38 in 30b0531

from utils.utils import get_admin_user

should be refactored as

from open_webui.utils.utils import get_admin_user

apps/utils/constants/config are very common module names and will conflict with other packages.

[tcztzy]

Maybe we should publish it firstly, use pipx will install package separated from other, therefore name conflict is not a big problem

[tjbck]

I'll prioritise this in the near future!