libvirt-python: 3.6.0 -> 3.8.0

This fixes an eval error introduced by
17a069276f.

The reason the evaluation fails is because there's an assertion on the
version of the Python library in order to be in par with the top-level
libvirt package.

Signed-off-by: aszlig <aszlig@nix.build>
Cc: @fpletz

pkgs/top-level/python-packages.nix

@@ -23982,13 +23982,13 @@ EOF
   };
 
   libvirt = let
-    version = "3.6.0";
+    version = "3.8.0";
   in assert version == pkgs.libvirt.version; pkgs.stdenv.mkDerivation rec {
     name = "libvirt-python-${version}";
 
     src = pkgs.fetchurl {
       url = "http://libvirt.org/sources/python/${name}.tar.gz";
-      sha256 = "1l0s9cx38qb6x5xj32r531xap11m93c3gag30idj8fzkn74cpfgc";
+      sha256 = "02spx8kfcsnqwsshd7bk2plyic2lbpwzg16sf3csh0avck5akjsz";
     };
 
     nativeBuildInputs = [ pkgs.pkgconfig ];