`ipyvuetify 3.0.0a3` appears to be missing fix #311 and still imports `nest_asyncio` unconditionally

Downstream prerelease CI started failing with ipyvuetify==3.0.0a3 after ipykernel==7.3.0 was released.

The failure is:

ModuleNotFoundError: No module named 'nest_asyncio'

Import chain:

pytest
-> pytest plugin autoload
-> solara
-> solara.components.file_drop
-> ipyvuetify.extra.FileInput
-> ipyvuetify.extra.file_input
-> import nest_asyncio

This looks like the old pre-#311 behavior, where ipyvuetify/extra/file_input.py imported nest_asyncio unconditionally at module import time.

However, #311 was merged on Apr 8, 2024:

fix: no hard dependency on nest_asyncio, use only when needed

That change made nest_asyncio optional and only required it when FileInput.readinto() is called from a thread with an event loop.

The current failure suggests that the published 3.0.0a3 artifact does not include #311, or that the 3.0 alpha release line was cut from stale/divergent code.

Why this surfaced now:

• On June 9, downstream CI installed ipykernel==7.2.0, which pulled in nest-asyncio==1.6.0.
• On June 11, downstream CI installed ipykernel==7.3.0, which switched to nest-asyncio2 (see https://github.com/ipython/ipykernel/pull/1499).
• Since nest-asyncio was no longer installed transitively, ipyvuetify==3.0.0a3 crashed while importing FileInput.

Expected behavior:

Importing ipyvuetify.extra.FileInput should not require nest_asyncio, matching the intent and implementation of #311.

Suggested upstream fix:

• publish a new 3.0.0a4 that includes #311; or
• yank/retract stale 3.0.0a* releases if the 3.0 alpha line is not intended for use; or
• otherwise ensure the 3.0 alpha branch contains the same optional nest_asyncio handling as master.

I do not think the correct fix is to add a hard dependency on nest-asyncio, because #311 explicitly changed the design to avoid a hard dependency and only require it when actually needed.

Start by comparing ipyvuetify/extra/file_input.py in the 3.0.0a3 artifact with the implementation from merged issue #311 and master. Verify that importing ipyvuetify.extra.FileInput works without nest_asyncio, then inspect the 3.0 alpha release state to determine whether a new artifact or release-line correction is needed.