chore: update Ruby OpenAPI Generator version

[jmlind]

This simply bumps the OpenAPI Generator version from v6.0.1 to v7.3.0

Related Issue or Design Document

This resolves an issue logged on the client-ruby repo. Summary:

Requests are still sent to the playground when base_url is set in OryClient.configure, and this was identified as an issue with the OpenAPI Generator which was fixed in v6.6.0. Thanks to @germs12 for the in-depth comment on that issue. https://github.com/ory/client-ruby/issues/1#issuecomment-1941598027

Checklist

• [x] I have read the contributing guidelines and signed the CLA.
• [x] I have referenced an issue containing the design document if my change introduces a new feature.
• [x] I have read the security policy.
• [x] I confirm that this pull request does not address a security vulnerability. If this pull request addresses a security vulnerability, I confirm that I got approval (please contact security@ory.sh) from the maintainers to push the changes.
• [x] I have added tests that prove my fix is effective or that my feature works.
• [x] I have added the necessary documentation within the code base (if appropriate).

Further comments