Upgrade Django to 5.2 LTS and align django-grappelli version

- Upgrade Django from 4.2.25 to 5.2 (LTS release)
- Update django-grappelli to >=3.0.3,<3.1 for compatibility

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: jontsai

requirements.txt

@@ -1,7 +1,7 @@
-Django>=4.2.25,<6
+Django>=5.2,<6
 Fabric==1.6.1
 South==0.8.4
-django-grappelli>=2.15.2
+django-grappelli>=3.0.3,<3.1
 emoji>=2.12.1,<3
 numpy>=1.26.0,<3
 pydantic>=1.10.13,<3