Python: Fix OpenAI assistant metadata type

[TaoChenOSU]

Motivation and Context

OpenAI Python SDK released 1.61.0 that contained a change which broke code.

Changes in the release: openai/openai-python@12b87a4

Description

This pull request includes several changes to the metadata type and the handling of metadata in various files, as well as updates to test files to reflect these changes. The most important changes include modifying the metadata type from dict[str, Any] to dict[str, str] and updating the tests to use json.dumps for metadata values.

Note: this is a breaking change because if users are not passing in the expected type before, they will need to update their code to pass in the correct type now.

Contribution Checklist

• The code builds clean without any errors or warnings
• The PR follows the SK Contribution Guidelines and the pre-submission formatting script raises no violations
• All unit tests pass, and I have added new tests where possible
• I didn't break anyone 😄

[markwallace-microsoft]

Python Test Coverage Report •

File	Stmts	Miss	Cover	Missing
semantic_kernel/agents/open_ai
azure_assistant_agent.py	110	4	96%	157, 159, 285, 302
open_ai_assistant_agent.py	111	5	95%	152, 154, 268, 288, 307
open_ai_assistant_base.py	521	13	98%	188, 197–202, 282, 298–299, 767, 821, 1027, 1035, 1120, 1184
TOTAL	17593	2359	87%

Python Unit Test Overview

Tests	Skipped	Failures	Errors	Time
3049	4 💤	0 ❌	0 🔥	1m 18s ⏱️