Remove unused serialize.py and deserialize.py modules

[jonathan343]

Summary

This PR removes the serialize.py and deserialize.py modules from aws-sdk-bedrock-runtime. This is cleanup that was missed in the v0.1.0 release. These modules were removed from code generation in smithy-lang/smithy-python#429. See the Smithy Python Serialization Design for more info.

Note

This also removes the following SyntaxWarning when using Python 3.14:

/Users/gytndd/dev/.venv/lib/python3.14/site-packages/smithy_aws_event_stream/_private/serializers.py:65: SyntaxWarning: 'return' in a 'finally' block
  return

Testing

Installed aws-sdk-bedrock-runtime locally after the changed and verified that calls with the invoke_model_with_bidirectional_stream and converse_stream still function as expected.

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