fix for ggplot2 labels change

[gravesti]

cf /tests/testthat/test-plots.R#L92-L158

ggplot2 is removing the labels component we are testing against. tidyverse/ggplot2#6290

Solution could be to use the new get_labs() tidyverse/ggplot2#6078 eg

p <- ggplot(mpg, aes(displ, hwy)) +
  geom_point(aes(colour = drv, shape = drv))

get_labs(p)