fix: skip nest_asyncio on Python 3.12+ to prevent uvicorn loop_factory error

[Kubudak90]

Problem

nest_asyncio.apply() patches asyncio.run() with a signature that doesn't support the loop_factory parameter added in Python 3.12. This causes uvicorn (and other modern async frameworks) to fail with:

TypeError: _patch_asyncio.<locals>.run() got an unexpected keyword argument 'loop_factory'

This was reported in #591.

Solution

Only apply nest_asyncio on Python < 3.12 where the patch is safe. On Python 3.12+, the standard asyncio behavior is preserved, allowing uvicorn and other frameworks to use the new loop_factory parameter.

Changes

• Added import sys at the top of the file
• Moved import nest_asyncio inside the version check block
• Wrapped the nest_asyncio.apply() call in a sys.version_info < (3, 12) condition

Testing

This fix ensures:

1. Python 3.10 and 3.11 continue to work with nested event loops via nest_asyncio
2. Python 3.12+ works with modern async frameworks like uvicorn that use loop_factory
3. The existing error handling for uvloop incompatibility is preserved

Fixes #591

[cb-heimdall]

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[Kubudak90]

Closing in favor of #637 which has a more comprehensive solution