fix: avoid Pydantic namespace shadowing in Message.parse

[AndersonBY]

Generated Pydantic dataclasses can use a module-level data alias for nested enums. Message.parse(data) currently keeps its bytes parameter in the local frame while constructing the dataclass; Pydantic lazy forward-reference resolution can then resolve data.SomeEnum against bytes and fail on a legal payload.

This patch deletes the parameter after creating the BytesIO stream, before constructing the message. It preserves positional and keyword call compatibility and adds regression coverage for both forms using the generated-module shape.

Validated on Python 3.12 with the 0.9.1 library source and Pydantic 2.13.x.