CLSA-2026-1784621612 Fix CVE(s): CVE-2025-43965, CVE-2026-61866

SECURITY UPDATE: memory leak in the JNG encoder when opening the alpha blob fails - debian/patches/CVE-2026-61866.patch: destroy the cloned jpegimage and jpegimageinfo before raising the writer exception in WriteOneJNGImage in coders/png.c - CVE-2026-61866...