"no module named 'usocket'" on Raspberry Pico W

Hi,

I'm trying to use this package in order to run an HTTP Server (Microdot) concurrently with other tasks on Raspberry Pico W.
It's failing for me with:
```
Traceback (most recent call last):
File "", line 42, in
File "microdot_asyncio.py", line 320, in run
File "asyncio/core.py", line 297, in run
File "asyncio/core.py", line 261, in run_until_complete
File "asyncio/core.py", line 246, in run_until_complete
File "microdot_asyncio.py", line 278, in start_server
File "asyncio/stream.py", line 226, in start_server
ImportError: no module named 'usocket'
```

Am I doing something totally unsupported yet, like maybe only some subset of CircuitPython devices have `usocket`?

I know that sockets generally work if I use `socketpool` for screating sockets, so maybe I'm really looking after https://github.com/adafruit/Adafruit_CircuitPython_asyncio/issues/4 ?

I'd appreciate any pointers!

Reproduce the failure on a Raspberry Pico W and trace the call path through microdot_asyncio.py, asyncio/stream.py, and asyncio/core.py. Read the referenced Adafruit_CircuitPython_asyncio issue and the 36-comment thread to determine whether this environment is supported; done means the support status and required change or limitation are established.

Written by the indexing model from the issue text.