Removing deprecation warning from asyncio.wait in advanced websockets example

[yyunikov]

Additions

• None

Removals

• None

Changes

• advance_websocket.py: adding asyncio.create_task() fixes deprecation warning "DeprecationWarning: The explicit passing of coroutine objects to asyncio.wait(). Based on official docs this will be removed in version 3.11.

Testing Steps

• run advance_websocket.py along with advance_client.html and play with the app. no warning should appear no longer.

Notes

• I was running the examples with Python 3.9.10 and these warnings were observed there
• Running with Python 3.10 was adding additional warnings and wasn't working at all, submitted an issue Websockets examples are not working with Python 3.10 #3 to fix this