DEV: Use a special import to declare font faces (#10583)

Update discourse-fonts to v0.0.3.

Follow-up to 7b7357147e.

config/initializers/014-track-setting-changes.rb

@@ -27,6 +27,8 @@ DiscourseEvent.on(:site_setting_changed) do |name, old_value, new_value|
     end
   end
 
+  Stylesheet::Manager.clear_core_cache!(["desktop", "mobile", "admin"]) if name == :base_font
+
   Report.clear_cache(:storage_stats) if [:backup_location, :s3_backup_bucket].include?(name)
 
   if name == :slug_generation_method