Update the grape-swagger gem

What does this MR do and why?

This closes the loop on #377941 by switching OpenAPI spec generation to use gitlab-grape-swagger instead of grape-swagger. This MR also includes the latest generated OpenAPI spec.

With the https://github.com/ruby-grape/grape-swagger/pull/872 merged, we can safely update the grape-swagger gem, to resolve the Could not resolve reference ($ref) bug.

The gem updates were done in accordance to https://docs.gitlab.com/ee/development/gemfile.html.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.