gnu: Add julia-plotthemes.

* gnu/packages/julia-xyz.scm (julia-plotthemes-0.4.0): New variable.

gnu/packages/julia-xyz.scm

@@ -1415,3 +1415,27 @@ applications")
     (description "This Julia package provides an interface to the GR
 visualization framework.")
     (license license:expat)))
+
+(define-public julia-plotthemes
+  (package
+    (name "julia-plotthemes")
+    (version "0.4.0")
+    (source
+     (origin
+       (method git-fetch)
+       (uri (git-reference
+             (url "https://github.com/JuliaPlots/PlotThemes.jl")
+             (commit (string-append "v" version))))
+       (file-name "PlotThemes")
+       (sha256
+        (base32 "0q6s3bwds1k1xcryj0y33l6lw0bl9kj6ljd0ph7rii445b7a9sk4"))))
+    (propagated-inputs `(("julia-plotutils" ,julia-plotutils)
+                         ("julia-requires" ,julia-requires)))
+    (build-system julia-build-system)
+    (home-page "https://github.com/JuliaPlots/PlotThemes.jl")
+    (synopsis "PlotThemes is a package to spice up the plots made with
+@code{Plots.jl}")
+    (description "Custom plotting themes for @code{Plots.jl}, including both
+light and dark themes.")
+    (license license:expat)))
+    (license license:expat)))