Fix bug that prevented user with external nginx from launch

The backslash was missing and prevented users from starting the bot

roles/matrix-bot-maubot/templates/systemd/matrix-bot-maubot.service.j2

@@ -28,7 +28,7 @@ ExecStart={{ matrix_host_command_docker }} run --rm --name matrix-bot-maubot \
 			{% endfor %}
 			--network={{ matrix_docker_network }} \
 			{% if matrix_bot_maubot_management_interface_http_bind_port %}
-			-p {{ matrix_bot_maubot_management_interface_http_bind_port }}:{{ matrix_bot_maubot_management_interface_port }}
+			-p {{ matrix_bot_maubot_management_interface_http_bind_port }}:{{ matrix_bot_maubot_management_interface_port }} \
 			{% endif %}
 			{{ matrix_bot_maubot_docker_image }} \
  			python3 -m maubot -c /config/config.yaml --no-update