fix: replace asyncio default event loop with uvloop

[asvishnyakov]

This is my proposed solution to #1789. Feel free to edit or close if I'm wrong

[willydouhard]

Unfortunately I don't think this is possible, we need re-entrancy for stuff like AskUser

[dokterbob]

Unfortunately I don't think this is possible, we need re-entrancy for stuff like AskUser

But then the tests are passing.

@asvishnyakov Does this mean we can do away with the asyncio dependency?

As I'm not (yet) convinced there's a strong use case for this and @willydouhard suggests it's not possible, I propose we leave this open for a bit until either:

1. A benchmark clearly shows there's performance issues in the current version.
2. Other contributors weigh in on this and/or are able to do additional testing.

The rationale being: if it's not (demonstrably) broken...

[asvishnyakov]

@dokterbob I’m new to Python, so I’m not entirely sure myself 😄. I’m trying to investigate performance issues in my app, and while this is definitely not a bottleneck, I was surprised to see it working better after the change. I think we need proper performance tests. Also, it looks like, as a workaround, I can run chainlint as a sub-app and configure uvloop for the main app, if needed.