Fix output_json with custom OpenAI APIs

[devin-ai-integration]

Fix output_json with custom OpenAI APIs

Fixes #2282

Problem

When using custom OpenAI-compatible APIs like Open-WebUI with Ollama, tasks with output_json fail with the error "Instructor does not support multiple tool calls, use List[Model] instead."

Solution

• Modified InternalInstructor to use PARALLEL_TOOLS mode when dealing with custom OpenAI APIs
• Added handling for list responses from the instructor library
• Added tests to verify the fix

Testing

• Added unit tests for the InternalInstructor class
• Verified that the fix works with mocked custom OpenAI responses
• Ran the full test suite to ensure no regressions

Link to Devin run: https://app.devin.ai/sessions/b7c7b68175c647acb3a0d58e19ce6e97
Requested by: Joe Moura (joao@crewai.com)

[devin-ai-integration]

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[devin-ai-integration]

Closing due to inactivity for more than 7 days.