Bumps {rmarkdown} minimal version (#68)

# 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.

DESCRIPTION

@@ -27,7 +27,7 @@ Suggests:
     dplyr (>= 1.0.3),
     knitr (>= 1.42),
     Matrix,
-    rmarkdown (>= 2.19),
+    rmarkdown (>= 2.23),
     testthat (>= 3.0.4),
     tidyr (>= 0.8.3)
 VignetteBuilder: