CVE-2026-7210: seed pyexpat/_elementtree with 16-byte XML hash salt via XML_SetHashSalt16Bytes; detect the symbol at runtime through a weak declaration so the fix engages against system libexpat 2.5.0 with the CVE-2026-41080 backport; add hard Requires on expat >= 2.5.0-1.el9_2.tuxcare.els12