Upgrade Synapse (1.12.3 -> 1.12.4)

roles/matrix-synapse/defaults/main.yml

@@ -5,7 +5,7 @@ matrix_synapse_enabled: true
 
 matrix_synapse_container_image_self_build: false
 
-matrix_synapse_docker_image: "matrixdotorg/synapse:v1.12.3"
+matrix_synapse_docker_image: "matrixdotorg/synapse:v1.12.4"
 matrix_synapse_docker_image_force_pull: "{{ matrix_synapse_docker_image.endswith(':latest') }}"
 
 matrix_synapse_base_path: "{{ matrix_base_data_path }}/synapse"