Update http dependency to match main mastodon development build

[RemusCourtenay]

Hi there,

I'm currently using this gem to develop on top of the main mastodon project version 3.5.3.
The gemfile that comes with 3.5.3 has http ~> 5.1 which causes installation of this gem to fail as it depends on http ~> 3.3, see the following error.

This can be fixed by setting the http version back down to 3.3 but I'm unsure if this will cause issues for other, more up to date, gems down the line.

[dbreunig]

Also there's a known error in http 3.3.0 that I'm hitting which has since been fixed. Linked here.

I have posted a pull request: #53