www/py-social-auth-app-django: Backport fix for CVE-2025-61783

• The issue was fixed in release 5.6.0, which, however, only supports Django versions from 5.1 onwards.

• Bump PORTREVISION due package change.

MFH: 2025Q4
Security: 3116b6f3-b433-11f0-82ac-901b0edee044