我正在尝试将气流设置为 systemd 服务。每次都失败并出现以下错误：
airflow[28159]: args.func(args)
airflow[28159]: File "/opt/py37/lib/python3.7/site-packages/airflow/cli/cli_parser.py", line 48, in command
airflow[28159]: return func(*args, **kwargs)
airflow[28159]: File "/opt/py37/lib/python3.7/site-packages/airflow/utils/cli.py", line 89, in wrapper
airflow[28159]: return f(*args, **kwargs)
airflow[28159]: File "/opt/py37/lib/python3.7/site-packages/airflow/cli/commands/webserver_command.py", line 483, in webserver
airflow[28159]: gunicorn_master_proc = subprocess.Popen(run_args, close_fds=True)
airflow[28159]: File "/usr/local/lib/python3.7/subprocess.py", line 800, in __init__
airflow[28159]: restore_signals, start_new_session)
airflow[28159]: File "/usr/local/lib/python3.7/subprocess.py", line 1551, in _execute_child
airflow[28159]: raise child_exception_type(errno_num, err_msg, err_filename)
airflow[28159]: FileNotFoundError: [Errno 2] No such file or directory: 'gunicorn': 'gunicorn'
可以为此做些什么？