Add missing 3.13 classifier

Author: thibaudcolas

pyproject.toml

@@ -20,6 +20,7 @@ classifiers = [
     "Programming Language :: Python :: 3.10",
     "Programming Language :: Python :: 3.11",
     "Programming Language :: Python :: 3.12",
+    "Programming Language :: Python :: 3.13",
     "Framework :: Django",
     "Framework :: Django :: 4.2",
     "Framework :: Django :: 5.0",