Fix OpenStruct use in import_github_spec
What does this MR do and why?
Fixes OpenStruct use in spec/requests/api/import_github_spec.rb
as Ruby 3 discourages it.
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.
Related to #344279