fix: threading approach in run_async_in_sync didn't wait for all tasks to complete

[njbrake]

Description

Fix the error when running tasks in threads

PR Type

🐛 Bug Fix ## Relevant issues

Checklist

• I have added unit tests that prove my fix/feature works
• New and existing tests pass locally
• Documentation was updated where necessary
• I have read and followed the contribution guidelines```

[codecov]

Codecov Report

❌ Patch coverage is 46.66667% with 8 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
src/any_llm/utils/aio.py	46.66%	7 Missing and 1 partial ⚠️

Files with missing lines	Coverage Δ
src/any_llm/utils/aio.py	54.16% <46.66%> (+7.10%)	⬆️

... and 28 files with indirect coverage changes

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