Replace deprecated to_dict with model_dump for Pydantic v2 compatibility

[timonrieger]

Description

This pull request updates code generation to replace the deprecated to_dict() method from Pydantic v2 models with the recommended model_dump() method.
Verified that generated models using Pydantic v2 successfully serialize with model_dump() and produce the same output as before by running a unittest with this code.

import unittest
import json
from pydantic import BaseModel, Field
  
class MyModel(BaseModel):
    id: int = Field(alias="identifier")
    name: str
    optional_field: str | None = None
  
    def to_dict(self):
        # Simulate old deprecated behavior (Pydantic v2 removed it)
        return self.model_dump(by_alias=True, exclude_unset=True)
  
    def old_json(self):
        return json.dumps(self.to_dict())
  
    def new_json(self):
        return json.dumps(self.model_dump(by_alias=True, exclude_unset=True))
  
class TestModelSerialization(unittest.TestCase):
    def test_json_output_equivalence(self):
        model = MyModel(identifier=1, name="Test")
        self.assertEqual(model.old_json(), model.new_json())
  
if __name__ == "__main__":
    unittest.main()

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[wing328]

thanks for the pr

can you please the ci test failure when you've time?

[timonrieger]

yes will do!

[timonrieger]

oh my bad actually. to_dict is not a pydantic method but a proprietary function in the codebase. In this function model_dump is already called. Thus, since this PR is is obsolete now, I will close it. The only thing to be done might be the removal of the comment line # TODO: pydantic v2: use .model_dump_json(by_alias=True, exclude_unset=True) instead