ggplot wrapper function that provide their own theme() instructions do not use our default theme

[Bisaloo]

e.g., plot.incidence() in

episoap/inst/rmarkdown/templates/transmissibility/skeleton/skeleton.Rmd

Lines 341 to 343 in 0c525bd

	dat_i %>%
	plot(alpha = 1, nrow = n_groups) +
	labs(title = "Incidence of cases over time")

We need to re-specify the theme here.

It probably affects some chunks in the EpiNow child document as well.