[CI][R]: R's nightly backwards compatibility job is failing to setup.

[jonkeane]

Describe the enhancement requested

Something is up with the way we're setting up (or possibly with Posit's Public Package Manager), since we install R version 4.4, but the error is complaining about version 3.0.0.

Run install.packages(c("remotes", "testthat"))
Installing packages into ‘/home/runner/work/_temp/Library’
(as ‘lib’ is unspecified)
Warning: Warning: unable to access index for repository https://packagemanager.rstudio.com/cran/__linux__/jammy/latest/src/contrib
Warning: Warning: unable to access index for repository https://cran.rstudio.com/src/contrib
Warning message:
packages ‘remotes’, ‘testthat’ are not available (for R version 3.0.0) 
Error: Error in loadNamespace(name) : there is no package called ‘remotes’
Calls: :: ... tryCatch -> tryCatchList -> tryCatchOne -> <Anonymous>

https://github.com/ursacomputing/crossbow/actions/runs/15090630647/job/42418790800

Component(s)

R, Continuous Integration

[thisisnic]

Closing this as we've stopped enforcing backwards compatibility - feel free to reopen if we still need it!