Indicate support for Python 3.13

Author: Qalthos

setup.cfg

@@ -33,6 +33,7 @@ classifiers =
   Programming Language :: Python :: 3.10
   Programming Language :: Python :: 3.11
   Programming Language :: Python :: 3.12
+  Programming Language :: Python :: 3.13
   Programming Language :: Cython
 
   Topic :: Software Development :: Libraries :: Python Modules