net/keycloak: Update 26.5.2 => 26.5.3

Release Notes:
https://www.keycloak.org/2026/02/keycloak-2653-released
https://github.com/keycloak/keycloak/releases/tag/26.5.3

PR: 293082
Security: CVE-2026-1609
Security: CVE-2026-1529
Security: CVE-2026-1486
Security: CVE-2025-14778
MFH: 2026Q1
(cherry picked from commit 53ed2d6632b1d550d80c91001ce319b54c4a4577)