Submission Checklist

• Run unit tests
• Declare copyright holder and agree to license (see below)

Summary

This issue: r-lib/pak#755 (also reported here: r-lib/actions#994)
impacts github actions setup-r-dependenceis of ubuntu latest intermittently. I haven't seen it on main yet, but has it me when testing on my fork: https://github.com/katrinabrock/cmdstanr/actions/runs/14448908294/job/40516367645 Thought it would be good to per-emptively prevent this from causing CI failures.

Copyright and Licensing

Please list the copyright holder for the work you are submitting
(this will be you or your assignee, such as a university or company):
Max Planck Institute of Animal Behavior

By submitting this pull request, the copyright holder is agreeing to
license the submitted work under the following licenses:

• Code: BSD 3-clause (https://opensource.org/licenses/BSD-3-Clause)
• Documentation: CC-BY 4.0 (https://creativecommons.org/licenses/by/4.0/)