add rmarkdown to VignetteBuilder (#792)

fix nosuggest ci

Author: pawelru

DESCRIPTION

@@ -79,7 +79,8 @@ Suggests:
     testthat (>= 3.1.9),
     withr (>= 2.0.0)
 VignetteBuilder:
-    knitr
+    knitr,
+    rmarkdown
 Config/Needs/verdepcheck: haleyjeppson/ggmosaic, tidyverse/ggplot2,
     rstudio/shiny, insightsengineering/teal,
     insightsengineering/teal.transform, mllg/checkmate, tidyverse/dplyr,