Label greek letters

[mweberr]

Currently greek letters are not correctly plotted. See the following example

library(ggplot2)
library(patchwork)

p1 <- ggplot(mtcars) + geom_point(aes(mpg, disp))
p2 <- ggplot(mtcars) + geom_boxplot(aes(gear, disp, group = gear)) + labs(x="μl blood")
ggsave(filename="Test.pdf",plot=p2)
## No Problems

p3 <- p1 + p2
ggsave(filename="Test.pdf",plot=p3)
## Warnings