try to use other mount option

to prevent docker from using dir instead of file

roles/matrix-sms-bridge/templates/systemd/matrix-sms-bridge.service.j2

@@ -27,7 +27,7 @@ ExecStart=/usr/bin/docker run --rm --name matrix-sms-bridge \
 			{% endif %}
 			-v {{ matrix_sms_bridge_config_path }}:/config:z \
 			-v {{ matrix_sms_bridge_data_path }}:/data:z \
-			-v {{ matrix_sms_bridge_data_path }}/gammu-smsdrc:/etc/gammu-smsdrc:z \
+			--mount type=bind,source={{ matrix_sms_bridge_data_path }}/gammu-smsdrc,target=/etc/gammu-smsdrc \
 			--device {{ matrix_sms_bridge_gammu_modem }}:/dev/ttyModem \
 			{% for arg in matrix_sms_bridge_container_extra_arguments %}
 			{{ arg }} \