Update pydantic versioning

[oddaspa]

Describe the bug
Outdated validation:

pyclarify/client.py:1036: PydanticDeprecatedSince20: The `validate_arguments` method is deprecated; use `validate_call` instead. Deprecated in Pydantic V2.0 to be removed in V3.0. See Pydantic V2 Migration Guide at https://errors.pydantic.dev/2.11/migration/
  @validate_arguments

To Reproduce
Steps to reproduce the behavior:

import pyclarify

Expected behavior
No warnings when loading module.

** System information (please complete the following information):**
OS: macOS 15.6.1
Python Version: 3.13.5
SDK Version: 0.6.7