`skip_if_offline()` complaining about missing curl package on ghactions but curl is installed

[gavinsimpson]

I've started seeing this error in R CMD check runs on ghactions:

<rlib_error_package_not_found/rlang_error/error/condition>
Error in `skip_if_offline()`: The package "curl" is required.
Backtrace:
    ▆
 1. └─testthat::skip_if_offline() at test-draw-parametric-effects.R:163:3
 2.   └─rlang::check_installed("curl")

but as far as I can tell, curl is installed during the dependency resolution step of the workflow: https://github.com/gavinsimpson/gratia/actions/runs/9113727769/job/25055965022#step:8:6706

Am I missing something here?

The r-lib workflow that sets up the dependencies will install all the dependencies of testthat which includes curl - I presume that's why curl is being installed anyway. And the session_info() output I linked to suggests curl was installed OK.

I've also deleted caches to force reinstalling packages.