RTools45 compatibility

[andrjohns]

Submission Checklist

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

Summary

R4.5 and RTools4.5 will be releasing soon, so we need to add handling for the new version. I think we'll probably also need to do another release (just a v0.9, not the full v1.0) so that users can pickup the binaries from R-Universe

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]

MacOS r-devel failures are unrelated, there are currently issues with their changes to handling libintl: https://stat.ethz.ch/pipermail/r-sig-mac/2025-March/015125.html

[jgabry]

Great, looks good.

I think we'll probably also need to do another release (just a v0.9, not the full v1.0) so that users can pickup the binaries from R-Universe

Ok, I guess in that case it's good I haven't merged #1061 yet. We can wait to merge that until after v0.9.