Re-add support for Ruby 2.4+

[iMacTia]

Description

Re-add support for Ruby 2.4+
Fixes #1369

[olleolleolle]

👍

[iMacTia]

Will need to re-release faraday-multipart and faraday-retry to support Ruby 2.4+ or Ruby 2.5+, but I'll leave this for later as it's not as urgent

[Justin-W]

Will need to re-release faraday-multipart and faraday-retry to support Ruby 2.4+ or Ruby 2.5+, but I'll leave this for later as it's not as urgent

@iMacTia The removal of support for Ruby v2.4 from faraday-retry is currently breaking some of our automation. We'd like to see that regression fixed ASAP.

[ccdredzik]

@iMacTia It is interesting that some do update their faraday library, but can't do so for the ruby version they're running. 2.4 is dead, so is 2.5. Don't resurrect them.

[iMacTia]

I'd normally agree but since I messed up a bit with the releases yesterday and that it didn't cost me much in the end, I re-added both in a fix release for 1.9.

That said, Faraday 2.0 will not support anything below 2.6 and we will drop EOL'ed support, even on minor version bumps, if it becomes a problem to support them