Add support for the new Faraday streaming API

[iMacTia]

Description

Add support for the new Faraday streaming API (see original issue)

Testing

Tested with the following script (adapter from the one in the issue)

require 'webmock'
require 'faraday'
require 'faraday/net_http'
require 'faraday/follow_redirects'

include WebMock::API
WebMock.enable!

stub_request(:get, 'https://www.example.com')
  .to_return(body: 'You are being redirected',
             status: [302, 'Content moved'],
             headers: { 'Location' => 'https://example.com' })

stub_request(:get, 'https://example.com')
  .to_return(body: 'You have arrived')

client = Faraday.new do |f|
  f.use Faraday::FollowRedirects::Middleware
end

client.get('https://www.example.com') do |req|
  req.options.on_data = proc do |chunk, _size, env|
    puts "got: #{chunk}" if env.status < 300
  end
end

this now outputs only the following:

got: You have arrived

Additional Notes

This change relies on new APIs introduced with Faraday 2.5 and is therefore incompatible with Faraday 2.4 and prior.
For this reason, these changes need to be released as a new v3.0 of the adapter, to avoid existing applications erroneously pulling this version while still using Faraday 2.4.

This problem affects this adapter only as it's a dependency of Faraday (default adapter).
Other adapters can specify the version of faraday in their Gemfile and therefore won't require a new major version.

[olleolleolle]

👍 Thanks for providing the additional context in the PR description, that helps.

[iMacTia]

Thanks for the quick review 🚀 !