graphics/png: security update to 1.6.52

Note this isn't the offered patch from the PR, but one that
instead puts the APNG patch version into a variable.

Reported by: FiLiS
Approved by: desktop@ (vishwin)
PR: 291266
MFH: 2025Q4 (after a few days)

png -- Multiple vulnerabilities
Security: CVE-2025-64505
Security: CVE-2025-64506
Security: CVE-2025-64720
Security: CVE-2025-65018
Security: 4b297f5a-cbad-11f0-ac9f-b42e991fc52e

png -- Out-of-bounds read
Security: CVE-2025-66293
Security: f323f148-d181-11f0-841f-843a4b343614