ggplot2 deprecation warning

[ConnorDonegan]

When the development version of ggplot2 installed, loading the development version of rstan gives:

library(rstan)
...
Warning message:
The `size` argument of `element_line()` is deprecated as of ggplot2 3.4.0.
Please use the `linewidth` argument instead.

This also appears when I send my rstan-dependent R package to win-builder to check it on the development version of R.

This traces back to:

 17. rstan (local) fun(libname, pkgname)
 18. rstan:::set_rstan_ggplot_defaults()
 22. ggplot2::element_line(size = 1)

which I guess needs to be changed to ``ggplot2::element_line(linewidth = 1)`, although I don't know where that line of code is.

RStan Version:

> packageVersion("rstan")
[1] ‘2.26.13’