feat: remove unused variable from meson.build

Author: tfuxu

meson.build

@@ -18,7 +18,6 @@ dependency('gtk4', version: '>= 4.0.0')
 glib_compile_resources = find_program('glib-compile-resources', required: true)
 glib_compile_schemas = find_program('glib-compile-schemas', required: true)
 desktop_file_validate = find_program('desktop-file-validate', required: false)
-appstream_util = find_program('appstream-util', required: false)
 
 cargo = find_program('cargo', required: true)