Merge https://github.com/google/adk-python/pull/1451
## Description
Fixes https://github.com/google/adk-python/issues/1306 by using `async for` with `await self.llm_client.acompletion()` instead of synchronous `for` loop.
## Changes
- Updated test mocks to properly handle async streaming by creating an async generator
- Ensured proper parameter handling to avoid duplicate stream parameter
## Testing Plan
- All unit tests now pass with the async streaming implementation
- Verified with `pytest tests/unittests/models/test_litellm.py` that all streaming tests pass
- Manually tested with a sample agent using LiteLLM to confirm streaming works properly
# Test Evidence:
https://youtu.be/hSp3otI79DM
Let me know if you need anything else from me for this PR
COPYBARA_INTEGRATE_REVIEW=https://github.com/google/adk-python/pull/1451 from avidelatm:fix/litellm-async-streaming d35b9dc90b2fd6fad44c3869de0fda2514e50055
PiperOrigin-RevId: 774835130
Copybara import of the project:
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824b4379d59a375191f8ce10997efd4021d5d0b3 by Andres Videla <andres.videla@trademe.co.nz>:
Adding regex for claude-4 models to anthropic_llm and updating tests
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8fa2a2df1931026dc803eee0e9b60e82e90c9efa by Wei Sun (Jack) <Jacksunwei@gmail.com>:
Adds trailing comma.
COPYBARA_INTEGRATE_REVIEW=https://github.com/google/adk-python/pull/934 from avidelatm:feature/add-support-for-claude-4-models-to-anthropic_llm 8d10bacdbec952ec9832180ac6c1d220916641da
PiperOrigin-RevId: 764396694
avidelatmandCopybara-Service