gnu: r-plotrix: Update to 3.7-6.

* gnu/packages/statistics.scm (r-plotrix): Update to 3.7-6.

gnu/packages/statistics.scm

@@ -2537,13 +2537,13 @@ disk (or a connection).")
 (define-public r-plotrix
   (package
     (name "r-plotrix")
-    (version "3.7-5")
+    (version "3.7-6")
     (source (origin
               (method url-fetch)
               (uri (cran-uri "plotrix" version))
               (sha256
                (base32
-                "0k6ivryac1k81z2dijjds376a9jxwk8rf5g48snj67cnjffkybxj"))))
+                "0ijfjlr7ls5hvfyzdmwab6bx0w3nvp0c8fgynj4355cj8mbzgmc3"))))
     (build-system r-build-system)
     (home-page "https://cran.r-project.org/web/packages/plotrix")
     (synopsis "Various plotting functions")