Update gitlab-duo-workflow-service-client gem from source

What does this MR do and why?

Update gitlab-duo-workflow-service-client gem from source

Follows https://gitlab.com/gitlab-org/modelops/applied-ml/code-suggestions/ai-assist/-/tree/main/clients/ruby#update-the-gem-in-the-gitlab-repository

References

• #417493 (closed)
• gitlab-org/modelops/applied-ml/code-suggestions/ai-assist!2524 (merged)

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