[PYTHON] generate code based on pydantic v2

[oshmoun]

In order to generate python clients with support for pydantic v2, some small adjustments are needed to the model templates.
This PR implements the changes, alongside a version update for pydantic in the various requirements lists

fixes #16468

@spacether (2019/11) ❤️ @krjakbrjak (2023/02)

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  ./bin/generate-samples.sh
  ./bin/utils/export_docs_generators.sh
  

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[UltimateLobster]

Hey! :D
I'm just a nobody who really wants to see this getting through. Thank you so much for doing this! This blocks my team from using openapi-generator (we use pydantic 2 features and the generated clients prevents us from installing them unless we switch back to pydantic 1)

I have a question though, won't this change break compatibilty with existing users? After all, you don't just add compatibility with pydantic 2, but also drop compatilibility with pydantic 1.

[oshmoun]

Thank you so much for doing this! This blocks my team from using openapi-generator (we use pydantic 2 features and the generated clients prevents us from installing them unless we switch back to pydantic 1)

Glad to know this proves helpful for somebody 🙂

I have a question though, won't this change break compatibilty with existing users? After all, you don't just add compatibility with pydantic 2, but also drop compatilibility with pydantic 1.

Well tbh I didn't consider that at all, and simply assumed that since the client is generated alongside dependencies (at default settings), it's ok to simply upgrade the whole thing and ignore backwards compatibility. Implementing such a thing would probably require introducing a new config parameter to select pydantic version. I'll leave that decision to people who have more experience with things openapi (I'm also a nobody who just wants this done 😁)

[wing328]

I've filed #16549 to add an option usePydanticV2 and add the ptestore samples but not all tests passed. Please take a look when you've time. Thanks.