gnu: r-scales: Update to 0.5.0.

* gnu/packages/statistics.scm (r-scales): Update to 0.5.0.
[propagated-inputs]: Add r-r6 and r-viridislite.

gnu/packages/statistics.scm

@@ -1000,13 +1000,13 @@ using just two functions: melt and dcast (or acast).")
 (define-public r-scales
   (package
     (name "r-scales")
-    (version "0.4.1")
+    (version "0.5.0")
     (source
      (origin
        (method url-fetch)
        (uri (cran-uri "scales" version))
        (sha256
-        (base32 "1lqccfmqdwrw0cjyqvw2zvgpk2jvnqrfb303l1raqyyf3zxqhav4"))))
+        (base32 "0zg9wfzmsdjxpbld0nzv7hcpq5r0wazqxmn7grvvif2agj0w1z6v"))))
     (build-system r-build-system)
     (propagated-inputs
      `(("r-dichromat" ,r-dichromat)
@@ -1014,7 +1014,9 @@ using just two functions: melt and dcast (or acast).")
        ("r-munsell" ,r-munsell)
        ("r-plyr" ,r-plyr)
        ("r-rcolorbrewer" ,r-rcolorbrewer)
-       ("r-rcpp" ,r-rcpp)))
+       ("r-rcpp" ,r-rcpp)
+       ("r-r6" ,r-r6)
+       ("r-viridislite" ,r-viridislite)))
     (home-page "https://github.com/hadley/scales")
     (synopsis "Scale functions for visualization")
     (description