Use Mint.HTTP1 in HTTP1 conn

[whatyouhide]

See #265 (comment).

[sneako]

Hey @whatyouhide ! Thanks for the PR. I guess we should also remove this part of the docs: https://github.com/sneako/finch/pull/250/files#diff-bfab6b899762596b9df3f3d7e719f23d973285f555d89dd956cfd59e652a7a25R60-R61

@wojtekmach want to make sure you see this, did you have any ideas for a workaround in Req?

[wojtekmach]

Wait are we basically reverting #250 or I'm missing something? It's fine if that is the plan i.e. we can't make it work but want to make sure.

[sneako]

Yeah that is what would happen if we merge this PR... I do think Req should be able to support arbitrary protocols for unknown hosts, so I'm not sure if we should proceed this way.

I guess the only alternative we have thought of so far is to "port HTTP/2 flow control in HTTP/1 connections" as @wojtekmach mentioned in the linked comment?

[whatyouhide]

Okay, let's close this and figure out a good solution in #265 first.