moving few packages from Imports to Suggests

[IndrajeetPatil]

Currently, paletteer imports a number of palette packages only for a single function (mostly here: https://github.com/EmilHvitfeldt/paletteer/blob/37567c57aae4ba4368ad964b457db8148b808ff5/R/paletteer_c_wrappers.R), and I was wondering if it would be better to use them conditionally and move them to Suggests in DESCRIPTION instead of directly importing them.

This would also slightly reduce dependency load for packages like ggstatsplot that rely on paletteer.

For example-

#' @rdname paleteer-c-wrapper
paletteer_c_scico <- function(name, n) {
if (!requireNamespace("scico", quietly = TRUE)) {
    stop("Package 'scico' needed. Please install it by running `install.packages('scico')`.")
  }  

scico::scico(n = n, palette = name)
}

What do you think?

[EmilHvitfeldt]

I like the idea! I'll try to whip it into the next update