test: add unit tests for pydantic utils (none_to_omit, parse_pydantic_error)

[eeshsaxena]

Description

composio/utils/pydantic.py had no dedicated test module. This adds tests/test_pydantic_utils.py covering:

• none_to_omit converting None to the omit sentinel while passing through other values (including falsy 0/"")
• parse_pydantic_error listing missing fields, reporting type errors with the offending parameter, and handling both together

No source changes.

Verification

pytest tests/test_pydantic_utils.py - 5 passed. ruff check / ruff format --check clean.

[vercel]

eeshsaxena is attempting to deploy a commit to the Composio Team on Vercel.

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[Alberto Schiabel (jkomyno)]

Thanks!