add django 6 classifier and upgrade lock file

Author: bckohan

pyproject.toml

@@ -15,7 +15,7 @@ keywords = [
     "enum",  "properties", "defines", "field", "django", "database",
     "bitmask", "mask", "bitfield", "flags"
 ]
-dependencies = ["django (>=3.2,<6.0)"]
+dependencies = ["django (>=3.2,<6.1)"]
 classifiers = [
     "Environment :: Console",
     "Framework :: Django",
@@ -29,6 +29,7 @@ classifiers = [
     "Framework :: Django :: 5.0",
     "Framework :: Django :: 5.1",
     "Framework :: Django :: 5.2",
+    "Framework :: Django :: 6.0",
     "Intended Audience :: Developers",
     "License :: OSI Approved :: MIT License",
     "Natural Language :: English",