feat: Add flag to not use alias for Pydantic’s json schema generation

[fbrueck]

I am using aliases to parse input data from camelCase to snake_case. I want to keep the snake_case for the Glue schema.

To do so, I need to pass the by_alias=False flag to Pydantic’s model_json_schema function.

The default behaviour remains unchanged.

Thank you for this nice little library :)

[svdimchenko]

@fbrueck thanks for your contribution! ❤️
Would you mind to add unit test for this feature ?
It would be nice to add this flag description to README.md

[fbrueck]

Thanks! I did add a test for argument parsing.

[svdimchenko]

Thanks! I did add a test for argument parsing.

Thanks for that, however I meant that it makes sense to add pydantic model example and expected results for case when by_alias flag is disabled.
Here are such tests examples: https://github.com/svdimchenko/pydantic-glue/blob/main/tests/unit/test_convert.py