Update setup.py

Author: C0rn3j

setup.py

@@ -1,8 +1,6 @@
 #!/usr/bin/env python3
-# -*- coding: utf-8 -*-
-#
-# Picard, the next-generation MusicBrainz tagger
-#
+"""Picard, the next-generation MusicBrainz tagger"""
+
 # Copyright (C) 2006-2008, 2011-2014, 2017 Lukáš Lalinský
 # Copyright (C) 2007 Santiago M. Mola
 # Copyright (C) 2008 Robert Kaye
@@ -824,6 +822,7 @@ def _get_requirements():
         'Programming Language :: Python :: 3.10',
         'Programming Language :: Python :: 3.11',
         'Programming Language :: Python :: 3.12',
+        'Programming Language :: Python :: 3.13',
         'Operating System :: MacOS',
         'Operating System :: Microsoft :: Windows',
         'Operating System :: POSIX :: Linux',