net/keycloak: Security update 26.7.2 => 26.7.3

Release Notes:
https://www.keycloak.org/2026/08/keycloak-2673-released

PR: 298077
Reported by: Matthias Wolf <freebsd@rheinwolf.de> (maintainer)
Approved by: osa, vvd (Mentors, implicit)
MFH: 2026Q3
Security: CVE-2026-35563
Security: CVE-2026-16093
Security: CVE-2026-16072
Security: CVE-2026-16108
Security: CVE-2026-16105
Security: CVE-2026-16089
Security: CVE-2026-16104
Security: CVE-2026-16106
Security: CVE-2026-17059
Security: CVE-2026-18218
Security: CVE-2026-18215
Security: CVE-2026-18201
Security: CVE-2026-18209
Security: CVE-2026-18214
Security: CVE-2026-18571
Security: CVE-2026-18572
Security: CVE-2026-18573
Security: CVE-2026-18570
Security: CVE-2026-19729
Security: CVE-2026-79652