gnu: graphviz: Update to 2.42.3.

* gnu/packages/graphviz.scm (graphviz): Update to 2.42.3.
[source](uri): Adjust for new download location.

gnu/packages/graphviz.scm

@@ -55,15 +55,15 @@
 (define-public graphviz
   (package
     (name "graphviz")
-    (version "2.40.1")
+    (version "2.42.3")
     (source (origin
               (method url-fetch)
               (uri (string-append
-                    "http://www.graphviz.org/pub/graphviz/ARCHIVE/graphviz-"
-                    version ".tar.gz"))
+                    "https://www2.graphviz.org/Packages/stable/portable_source/"
+                    "graphviz-" version ".tar.gz"))
               (sha256
                (base32
-                "08d4ygkxz2f553bxj6087da56a23kx1khv0j8ycxa102vvx1hlna"))))
+                "1pbswjbx3fjdlsxcm7cmlsl5bvaa3d6gcnr0cr8x3c8pag13zbwg"))))
     (build-system gnu-build-system)
     (arguments
      ;; FIXME: rtest/rtest.sh is a ksh script (!).  Add ksh as an input.