net/keycloak: Update 26.6.3 => 26.6.4 (8 CVEs)

Release Notes:
https://www.keycloak.org/2026/06/keycloak-2664-released

PR: 296367
Security: CVE-2026-9099
Security: CVE-2026-9083
Security: CVE-2026-9086
Security: CVE-2026-9705
Security: CVE-2026-9795
Security: CVE-2026-9799
Security: CVE-2026-9800
Security: CVE-2026-11800
Sponsored by: UNIS Labs
MFH: 2026Q2

(cherry picked from commit e9dd3d7873620832266a43b81635d2391d6668ed)