use async request library

[avaldebe]

Hi John,

Have you considered to use an asynchronous request library?
Replacing requests by aiohttp would give you concurrent downloads,
like in the 3rd implementation shown on this article.

Would you accept a PR?
I have no experience with async python, but I'm willing to give it a try.

Cheers,
Álvaro.

[JohnPaton]

Hey, thanks for checking out airbase! I've had something like this in mind for ages but just never got around to it. If I had done it myself I would probably go the concurrent.futures route, but I would certainly be open to a properly async PR if it remained backwards compatible!

[avaldebe]

[...] I would certainly be open to a properly async PR if it remained backwards compatible!

Would need to bump the minimum python version up to Python 3.7 in order to use aiohttp:
But I guess that would not be a problem, since older versions are out of support.
If so, would it be OK to take it one step further and bump it up to 3.8?

[JohnPaton]

Given that this is often used in an academic setting, older Python versions are more common than one might hope 😬 I'd prefer 3.7 for that reason.

[avaldebe]

I went a bit out of scope on PR #11.
Needed to type annotate quite a bit in order to figure find missing awaits and such errors.
I also added configurations for my standard python dev tools.
I'm happy to remove to revert the changes you find unnecessary .

[avaldebe]

Hi @JohnPaton

After adding type hints to all the functions, mypy found the following inconsistency.

request = AirbaseRequest() has request.country = None and request._country_list = [None], which will would crash on line 321.

airbase/airbase/airbase.py

Lines 313 to 324 in 8420903

	self._country_list = util.string_safe_list(country)
	self._shortpl_list = util.string_safe_list(shortpl)
	self._download_links = []
	for c in self._country_list:
	for p in self._shortpl_list:
	self._download_links.append(
	util.link_list_url(
	c, p, year_from, year_to, source, update_date
	)
	)

I'm aware that normal usage of the library would not generate such a request, but I think it would be better to remove the default value for country from AirbaseRequest.init`.