fix sytax errors with multiple auth types

[jonathan343]

Summary

This PR addresses a codegen bug that results in the following error when trying to generate a client that supports multiple auth schemes:

Projection client failed: software.amazon.smithy.codegen.core.CodegenException: Command `python3 -m ruff check --fix` failed with output:

src/aws_sdk_bedrock_runtime/models.py:648:1: SyntaxError: Expected ',', found name
    |
646 |         effective_auth_schemes = [
647 |             ShapeID("aws.auth#sigv4")
648 | ShapeID("smithy.api#httpBearerAuth")
    | ^
649 |         ]
650 | )
    |

Problem: Multiple ShapeId objects are getting added to the effective_auth_schemes list without a , delimiter, resulting in a SyntaxError.

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