Require registration token

Re SeaGL/attend.seagl.org#24

inventory/group_vars/matrix_servers.yml

@@ -17,6 +17,7 @@ matrix_server_fqn_matrix: "{{ now(fmt='%Y') }}-ephemeral.host.seagl.org"
 
 # Enable or disable this when the time is right
 matrix_synapse_enable_registration: true
+matrix_synapse_registration_requires_token: true
 
 matrix_client_element_enabled: false
 devture_playbook_state_preserver_vars_preservation_enabled: false