Release a 2.2.0

[olleolleolle]

• CHANGELOG items from v2.1.1...master - if you see something that's a feature, or notable, make a comment here, so we can source a CHANGELOG section for this version.
• bump minor (there are tiny features)
• release the gem

[olleolleolle]

Gem got modernized, too, sweet, @ioquatix

[olleolleolle]

While poking around, I saw that I needed to #87. So I did.

[ioquatix]

https://github.com/socketry/multipart-post/releases/tag/v2.2.0