Synapse Admin - use correct restrictBaseUrl data type by default

roles/custom/matrix-synapse-admin/defaults/main.yml

@@ -197,7 +197,7 @@ matrix_synapse_admin_configuration: "{{ matrix_synapse_admin_configuration_defau
 
 # Controls the restrictBaseUrl configuration setting, which, if defined,
 # restricts the homeserver(s), so that the user can no longer define a homeserver manually during login.
-matrix_synapse_admin_config_restrictBaseUrl: "{{ [matrix_homeserver_url] }}"  # noqa var-naming
+matrix_synapse_admin_config_restrictBaseUrl: "{{ matrix_homeserver_url }}"  # noqa var-naming
 
 # Controls the menu configuration setting, which, if defined, adds new menu items to the Synapse Admin UI.
 # The format is a list of objects, where each object has the following keys: