Ground work for integration tests with real instance

[erimicel]

Change Summary

Related: #42

This PR covers the groundwork for introducing integration/request tests with an actual Docker container;

• Adds Ruby 3.4 to CI Matrix
• Updates dev gems
• Making sure all collection tests using same schema structure
• Allow localhost requests in rspec with WebMock

PR Checklist

• I have read and signed the Contributor License Agreement.

[tharropoulos]

First of all, thank you for taking the time to implement those changes!

[tharropoulos]

Could we leave dep bumps until after we've merged the test changes? Would prefer to avoid any side effects related to deps here

[erimicel]

These updates only for dev dependencies, imo would be nice to update these to latest before hand?

Gem dependencies are declared in .gemspec file

[tharropoulos]

Most of the dep bumps are specifically for testing, so they should be fine. Although, I feel like they should be left as the last thing, so we don't need to bisect if something goes wrong with any dependency.