botocore: add dict type check before parsing tool_use from Bedrock messages

[SrdjanLL]

Description

Amazon Bedrock tool use extraction logic doesn't agree with som of the use cases (conversation construction), such as the case with pre-created assistant message:

'messages': [{"role": "user", "content": "Placeholder text."}, {"role": "assistant", "content": "{"}],

This PR addresses this by adding a dict type check on the message content before attempting to get the value of tool_usefrom the content.

Fixes #3500

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

• tox -e py312-test-instrumentation-botocore-0
• Smoke tested on previously created reproducer.

Does This PR Require a Core Repo Change?

• Yes. - Link to PR:
• No.

Checklist:

See contributing.md for styleguide, changelog guidelines, and more.

• Followed the style guidelines of this project
• Changelogs have been updated
• Unit tests have been added
• Documentation has been updated