fix: Declare support for Python 3.13 (#326)

Co-authored-by: Anthonios Partheniou <partheniou@google.com>

Author: hugovk

setup.py

@@ -81,6 +81,7 @@
         "Programming Language :: Python :: 3.10",
         "Programming Language :: Python :: 3.11",
         "Programming Language :: Python :: 3.12",
+        "Programming Language :: Python :: 3.13",
         "Operating System :: OS Independent",
         "Topic :: Internet",
     ],