Fix debug_info_spec.rb for rspec v3.12.0

What does this Merge Request do and why?

Upgrading rspec to 3.12.0 causes a spec failure: https://gitlab.com/gitlab-org/gitlab-development-kit/-/jobs/3260078850.

Merge Request checklist

• This change is backward compatible. If not, please include steps to communicate to our users.
• Tests added for new functionality. If not, please raise Issue to follow-up.
• Documentation added/updated, if needed.
• gdk doctor test added, if needed.
• Add the ~highlight label if this MR should be included in the CHANGELOG.md.