Native support for Pydantic models for function_framework.typed

Following https://github.com/GoogleCloudPlatform/functions-framework-python/pull/208#issuecomment-1832951749,
it will be great to have [Pydantic](https://docs.pydantic.dev/latest/) models supported natively. E.g.

```python

from pydantic import BaseModel

class HelloRequest(BaseModel):
name: str

@functions_framework.typed
def hello(hr: HelloRequest):
return f"Hello, {hr.name}"
```

Thank you!