Add async example

[frmdstryr]

For #510 . A similar approach can be used with other qt / asyncio libraries.

[codecov-commenter]

Codecov Report

Merging #511 (7a4c453) into main (bcfb9b7) will decrease coverage by 3.28%. The diff coverage is n/a.

:exclamation: Current head 7a4c453 differs from pull request most recent head c41d177. Consider uploading reports for the commit c41d177 to get more accurate results

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #511 +/- ## ========================================== - Coverage 74.59% 71.30% -3.29% ========================================== Files 302 308 +6 Lines 22944 22014 -930 Branches 2951 2961 +10 ========================================== - Hits 17114 15697 -1417 - Misses 4936 5420 +484 - Partials 894 897 +3 ```

[MatthieuDartiailh]

Could you rebase on main since to get green CIs ?

[MatthieuDartiailh]

Thanks

[Kochise]

Works with qasync, thanks.