Replace or remove nest_asyncio due to lack of maintenance

[danielnsilva]

Problem

The nest_asyncio package is no longer maintained due to the author's passing nearly a year ago, which is deeply saddening. This leaves the project without updates or support, potentially leading to future issues.

Context

• There are no active forks of the nest_asyncio to take over its maintenance.
• The ARM devlib project switched from nest_asyncio to greenlet to support nested event loops.
• Python has no plans to support nested event loops, so we can't count on this approach going forward.

[Chaoses-Ib]

I've made a fork of nest-asyncio to fix support for Python 3.12 and 3.14: nest-asyncio2. Since it's also used in my own project, I'm going to maintain it for a long time. There is no behavior change on Python < 3.12, and it's already tested with https://github.com/NVIDIA/NeMo-Agent-Toolkit, https://github.com/pyvista/pyvista, https://github.com/Chaoses-Ib/ComfyScript, so it should be a safe replacement.