[PULP-243] Bump ruby openapi-generator for core>=3.70

[pedro-psb]

Replaces: #101

Summary:

• Dependency errors: added faraday and faraday_http constraints. That's due to katello lowerbound ruby version (>=2.7) for the lower version supported on Pulp's matrix.
• Pathname (NameError): added require "pathname" in the api_client. The code was using this class/module (?) which was not being required (imported?) (ref). Didnt find similar cases in openapi-generator, so it's probably related to the restricted version set above.

[pedro-psb]

The CI is passing but it is not using nighly pulp (the pulp-ci-centos image is stable), so its not really testing the >=3.70 branch. Locally I'm hitting some ruby errors:

[2025-01-07T09:30:12.339682 #1444741] DEBUG -- : Calling API: UploadsApi.update ...
Traceback (most recent call last):
        20: from test_bindings.rb:102:in `<main>'
        19: from test_bindings.rb:72:in `upload_file_in_chunks'
        18: from test_bindings.rb:72:in `open'
        17: from test_bindings.rb:88:in `block in upload_file_in_chunks'

...

/tmp/ruby-venv/local/gems/gems/pulpcore_client-3.70.0.dev0/lib/pulpcore_client/api_client.rb:144:in
`block in build_request_body': uninitialized constant PulpcoreClient::ApiClient::Pathname (NameError)

[mdellweg]

This is exactly the way I expect the bindings to be patched.
I cannot say much about the actual changes in the ruby code.