Fix Github Workflows

[andrjohns]

Submission Checklist

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

Summary

Github has changed the MacOS runners to arm64, causing issues with the current cache.

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):
Andrew Johnson

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/)

[andrjohns]

Windows R-Devel failure is unrelated (stringi package broken).

Test Coverage failures also unrelated, they're giving a 429 HTTP code for the upload - indicating that we're just hitting a rate limit.