Relax required_ruby_version to support Ruby 4.0

[taketo1113]

This Pull Request relaxed the required_ruby_version to allow Ruby 4.0.

The current gemspec specifies an upper bound of "< 4", which prevents gem install faraday-multipart from working on Ruby 4.0, scheduled for release on December 25. By removing this upper bound, the gem will continue to work on Ruby 4.0 and future Ruby versions.

• Ruby 4.0.0 preview3 Released
  • https://www.ruby-lang.org/en/news/2025/12/18/ruby-4-0-0-preview3-released/

Additional Information

Bundler version for development / test environments

This Pull Request removes the development dependency on the bundler gem.
In Ruby 4.0, Bundler is provided as a default gem with version 4.0 or later.

faraday-multipart/Gemfile

Line 8 in b02f761

gem 'bundler', '~> 2.0'

Update CI Matrix

This Pull Request also:

• adds Ruby 3.2 - 4.0 to the CI matrix
• bumps actions/checkout from v4 to v6

[olleolleolle]

Thanks, @taketo1113 !

[taketo1113]

Thanks!

[chaadow]

can we get a release on rubygems please

[iMacTia]

Release 1.2.0 is now out with Ruby 4 support 🎉