Update pool url on redirect

[felixbrucker]

Purpose:

Support the migration of pool farmer api urls: when a pool changes its farmer api url, the client persists the new url to be able to continue to communicate with the pool should the old url stop working in the future.

Current Behavior:

Pools can already setup redirects to a new farmer api url and they will get used correctly, however the new url is not persisted by the client.

New Behavior:

When a url change is detected the new url is persisted.

[emlowe]

Needs a test to execise this code - take a look at test_farmer_pool_response

[felixbrucker]

Unfortunately i know too little of how the mocking in pytest works for the following scenario:
- mock GET for one url with a 307 redirect and location set to another url
- mock a second GET for the other url with a json response

It seems the currently used patch just overwrites what the specific aiohttp.ClientSession.* method returns, i'd need something like https://github.com/pnuckowski/aioresponses probably, or is something like this achievable with some kind of callback style return value where i do the matching myself?

Edit: or i just skip all the redirect logic in aiohttp and return the final response with the url being different from the requested url, thinking about that now it's probably the better way anyway as how redirects are handled by aiohttp is not in scope here. I'll implement a test using this later 👍

[felixbrucker]

@emlowe added tests 👍

[emlowe]

close and reopen to pickup hopefully some CI fixes

[emlowe]

coverage diff exemption