Suggestion: add async support and potentially move from `requests` to `httpx`

[p3zq]

Hi all,

I appreciate the effort you've put into this project. I was wondering if you are open for contributions that add asynchronous support for the library. If so, would you have any guidelines or concerns before I start? I'm happy to raise a PR and hear your thoughts.

My initial thinking would be to add relevant async equivalent functions with _async suffix to maintain backwards compatibility.

lightning1 = download_stored_query("fmi::observations::lightning::simple")
lightning2 = await download_stored_query_async("fmi::observations::lightning::simple")

This potentially would require switching from requests to e.g. httpx.

[pnuu]

Sorry for the very late response!

Please, do create a PR for the async variants! I don't have any experience with the asynchronous downloading, but see that it can be very useful. I'll try to remember and check the repository more regularly during the summer.