Change fake packages to use properties of the dependency package(s). (#8167)

Fix linter issues

Co-authored-by: chronos <noreply@github.com>

packages/libxml2_python.rb

@@ -1,11 +1,12 @@
 require 'package'
+require_relative 'py3_libxml2'
 
 class Libxml2_python < Package
-  description 'Dummy package for py3_libxml2'
-  homepage 'https://gitlab.gnome.org/GNOME/libxml2/'
-  version '1'
-  license 'MIT'
-  compatibility 'all'
+  description Py3_libxml2.description.to_s
+  homepage Py3_libxml2.homepage.to_s
+  version Py3_libxml2.version.to_s
+  license Py3_libxml2.license.to_s
+  compatibility Py3_libxml2.compatibility.to_s
 
   is_fake