Bumps {rmarkdown} minimal version (#759)

# Pull Request

Part of insightsengineering/coredev-tasks#546

Necessary bump to overcome a lack of binary on ppm snapshots that causes
an error on minimum strategies for `scheduled` workflows.

---------

Signed-off-by: André Veríssimo <211358+averissimo@users.noreply.github.com>

DESCRIPTION

@@ -70,6 +70,7 @@ Suggests:
     nestcolor (>= 0.1.0),
     pkgload,
     rlang (>= 1.0.0),
+    rmarkdown (>= 2.23),
     rtables (>= 0.6.6),
     rvest,
     shinytest2,
@@ -91,7 +92,7 @@ Config/Needs/verdepcheck: haleyjeppson/ggmosaic, tidyverse/ggplot2,
     daattali/colourpicker, daattali/ggExtra, aphalo/ggpmisc, aphalo/ggpp,
     slowkow/ggrepel, baddstats/goftest, gridExtra, ramnathv/htmlwidgets,
     jeroen/jsonlite, yihui/knitr, deepayan/lattice, MASS,
-    insightsengineering/nestcolor, r-lib/rlang,
+    insightsengineering/nestcolor, r-lib/rlang, rstudio/rmarkdown,
     insightsengineering/rtables, tidyverse/rvest, sparkline,
     rstudio/shinytest2, insightsengineering/teal.data, r-lib/testthat,
     r-lib/withr