Remove rworkflows from Suggests to fix macOS/Windows GHA

rworkflows is a CI infrastructure package, not used by any package
code. It's not on CRAN, so R CMD check fails on macOS/Windows where
_R_CHECK_FORCE_SUGGESTS_ is not set to false.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: bschilder

DESCRIPTION

@@ -40,7 +40,6 @@ Imports:
     methods,
     ggplot2
 Suggests:
-    rworkflows,
     markdown,
     rmarkdown,
     remotes,