keycloak: update quay.io/keycloak/keycloak Docker tag to v26.3.1

Author: renovate[bot]

keycloak/kustomization.yaml

@@ -22,4 +22,4 @@ generators:
   - secret-generator.yaml
 images:
   - name: quay.io/keycloak/keycloak
-    newTag: 26.1.4@sha256:044a457e04987e1fff756be3d2fa325a4ef420fa356b7034ecc9f1b693c32761
+    newTag: 26.3.1@sha256:d9b4b8ff1627e43472cee278bab2da8dafeb082144addd2bfb0faa56a9be47d6