www/unit: Deprecate and set expiration date to 2025-12-31

• Upstream repo archived on Oct 8 2025
• Import patch to fix build with PHP 8.5

References:
https://github.com/nginx/unit
https://github.com/nginx/unit/commit/ad736f9f4fddd844aed1eb6ee8a9dc88df5533fb

PR: 264442
Reported by: pkg-fallout