calibre: 2.50.1 -> 2.51.0

pkgs/applications/misc/calibre/default.nix

···
 }:
 
 stdenv.mkDerivation rec {
-  version = "2.50.1";
+  version = "2.51.0";
   name = "calibre-${version}";
 
   src = fetchurl {
     url = "http://download.calibre-ebook.com/${version}/${name}.tar.xz";
-    sha256 = "0fy5fwj53hl8bcl412d2y61xm1nmkry24dlanj07nn6dhmrs0cm9";
+    sha256 = "1rhpcxic4g2zyr5s3xn8dayyb45l9r8zyniaig8j7pl5kmsfjijn";
   };
 
   inherit python;