label testing for plots

[topepo]

          Hi Max, thanks for keeping vigilant and up to date! If you want to continue to test the labels, we also implemented an accessor (https://github.com/tidyverse/ggplot2/pull/6078) for exactly this reason.

Originally posted by @teunbrand in #951 (comment)

[topepo]

We should convert to using expect_snapshot(ggplot2::get_labs(p)) once the devel version of ggplot2 is out

[teunbrand]

The get_labs() function is included in the recently released hotfix (ggplot2 3.5.2) for forward compatibility reasons such as this.