arpack: version bump to 3.2.0

pkgs/development/libraries/science/math/arpack/default.nix

···
 { stdenv, fetchurl, gfortran, openblas }:
 
-let version = "3.1.5";
+let
+  version = "3.2.0";
 in
 stdenv.mkDerivation {
   name = "arpack-${version}";
   src = fetchurl {
-    url = "http://forge.scilab.org/index.php/p/arpack-ng/downloads/get/arpack-ng_${version}.tar.gz";
-    sha256 = "05fmg4m0yri47rzgsl2mnr1qbzrs7qyd557p3v9wwxxw0rwcwsd2";
+    url = "https://github.com/opencollab/arpack-ng/archive/${version}.tar.gz";
+    sha256 = "1fwch6vipms1ispzg2djvbzv5wag36f1dmmr3xs3mbp6imfyhvff";
   };
 
   buildInputs = [ gfortran ];