[change] Replaced jsonfield.JSONField with models.JSONField #181

Migrated from the third-party jsonfield package to Django's
built-in models.JSONField in sample app.

Fixes #181

Author: SAMurai-16

setup.py

@@ -19,6 +19,7 @@
     include_package_data=True,
     zip_safe=False,
     install_requires=[
+        "Django>=4.2",
         "cryptography~=46.0.3",
     ],
     classifiers=[