Add specific Django version to classifiers

Author: ulgens

pyproject.toml

@@ -5,6 +5,7 @@ description = "Source code to djangoproject.com"
 requires-python = ">=3.12"
 classifiers = [
     "Framework :: Django",
+    "Framework :: Django :: 6.0",
     "License :: OSI Approved :: BSD License",
     "Operating System :: OS Independent",
     "Programming Language :: Python :: 3 :: Only",