remove StatsPlots recipe warning

src/args.jl

@@ -1108,12 +1108,6 @@ function RecipesPipeline.preprocess_attributes!(plotattributes::AKW)
         plotattributes[:framestyle] = _framestyleAliases[plotattributes[:framestyle]]
     end
 
-    # warnings for moved recipes
-    st = get(plotattributes, :seriestype, :path)
-    if st in (:boxplot, :violin, :density) && !isdefined(Main, :StatsPlots)
-        @warn("seriestype $st has been moved to StatsPlots.  To use: \`Pkg.add(\"StatsPlots\"); using StatsPlots\`")
-    end
-
     return
 end