Update Keycloak database configuration to use 'databaseName' instead of 'database'

modules/servers/keycloak.nix

@@ -22,7 +22,7 @@ in
         type = "postgresql";
         host = config.my.postgresSocket;
         username = "keycloak";
-        database = "keycloak";
+        databaseName = "keycloak";
       };
       initialAdmin = {
         user = "admin";