fix(python): remove nest-asyncio dependency for Python 3.12+ compatibility

[Kubudak90]

Summary

Closes #591.

Removes the "nest-asyncio" dependency and replaces it with a thread-safe fallback in .

Problem

is incompatible with Python 3.12+ in environments using or other modern async loops, causing runtime errors when synchronous methods on are called from an already-running event loop.

Solution

If no event loop is running, uses directly.
If an event loop is already running, the coroutine is executed in a background thread, where can safely create a new loop.

This approach is standard, does not require patching the event loop, and works correctly across all supported Python versions.

Changes

• Removed and from
• Rewrote to use as a fallback
• Removed from dependencies
• Updated accordingly

Testing

• All 11 tests in pass
• Manually verified behavior in three scenarios:
  1. No running event loop
  2. Inside a running event loop
  3. Nested running event loops