gnu: racket: Update to 6.6

* gnu/packages/scheme.scm (racket): Update to 6.6.

gnu/packages/scheme.scm

@@ -5,6 +5,7 @@
 ;;; Copyright © 2016 Ricardo Wurmus <rekado@elephly.net>
 ;;; Copyright © 2016 Efraim Flashner <efraim@flashner.co.il>
 ;;; Copyright © 2016 Jan Nieuwenhuizen <janneke@gnu.org>
+;;; Copyright © 2016 ng0 <ng0@we.make.ritual.n0.is>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -402,7 +403,7 @@ implementation techniques and as an expository tool.")
 (define-public racket
   (package
     (name "racket")
-    (version "6.5")
+    (version "6.6")
     (source (origin
              (method url-fetch)
              (uri (list (string-append "http://mirror.racket-lang.org/installers/"
@@ -412,7 +413,7 @@ implementation techniques and as an expository tool.")
                          version "/racket/racket-" version "-src-unix.tgz")))
              (sha256
               (base32
-               "0gvh7i5k87mg1gpqk8gaq50ja9ksbhnvdqn7qqh0n17byidd6999"))))
+               "1kzdi1n6h6hmz8zd9k8r5a5yp2ryi4w3c2fjm1k6cqicn18cwaxz"))))
     (build-system gnu-build-system)
     (arguments
      '(#:phases