Allow emails to be sent again, #2101 #2172

Builds off !2951 (merged) to add a temporary fix for email, too.

Currently no emails can be sent without this, as Swoosh is dependent on Hackney, which was downgraded as a temporary solution to #2101 (closed). Requesting merge into stable branch.

Further context: https://github.com/swoosh/swoosh/issues/478#issuecomment-642393707

I confirmed on my own server that emails can be sent after this:

➜  pleroma git:(stable) ✗ mix pleroma.email test

20:19:31.583 [debug] QUERY OK source="config" db=35.1ms decode=4.7ms queue=60.4ms idle=0.0ms
SELECT c0."id", c0."key", c0."group", c0."value", c0."inserted_at", c0."updated_at" FROM "config" AS c0 []

20:19:31.599 [warn]  web_push_encryption is not started.

20:19:31.599 [warn]  ex_aws is not started.

20:19:31.599 [warn]  joken is not started.
Test email has been sent to [{"", "alex@alexgleason.me"}] from {"Gleasonator", "noreply@gleasonator.com"}