[BUG] Python - IDE Debug/Type Checking fails on configuration generated code - Typing issue

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator (example)?
• Have you tested with the latest master to confirm the issue still exists?
• Have you searched for related issues/PRs?
• What's the actual output vs expected output?
• [Optional] Sponsorship to speed up the bug fix or feature request (example)

Description

In the Python (after version 7.10), a type-checking issue occurs when running in debug mode in an IDE. The type check on configuration generation fails due to typing.Self being used incorrectly.

Error Trace:

../../../.pixi/envs/default/lib/python3.10/site-packages/dedak_meser/configuration.py:133: in <module>
    class Configuration:
../../../.pixi/envs/default/lib/python3.10/site-packages/dedak_meser/configuration.py:166: in Configuration
    _default: ClassVar[Optional[Self]] = None
../../../.pixi/envs/default/lib/python3.10/typing.py:309: in inner
    return func(*args, **kwds)
../../../.pixi/envs/default/lib/python3.10/typing.py:400: in __getitem__
    return self._getitem(self, parameters)
../../../.pixi/envs/default/lib/python3.10/typing.py:525: in Optional
    arg = _type_check(parameters, f"{self} requires a single type.")
../../../.pixi/envs/default/lib/python3.10/typing.py:169: in _type_check
    raise TypeError(f"Plain {arg} is not valid as type argument")
E   TypeError: Plain typing.Self is not valid as type argument

openapi-generator version

7.10.0

Generation Details

`openapi-generator-cli generate -g python -i openapi.json -o .generated/openapi -p packageVersion=$VERSION -p packageName=$PIXI_PROJECT_NAME`

Steps to reproduce

1. Use openapi genertor cli to generate
2. Use IDE (Pycharm 2024-2025) Debug mode with the generated package in code base imported

Related issues/PRs

In 7.10 they did this:
https://github.com/OpenAPITools/openapi-generator/pull/20014

Transition to backward-compatible typing for Python 3.10+.

Start by reproducing the issue with the shown openapi-generator-cli command and the generated Python package in an IDE using Python 3.10. Read the Python generator changes from related PR #20014 and trace the generated configuration.py typing; done means the generated package imports and debug/type checking no longer raises the reported TypeError.