在使用python 3.6.8的Ubuntu 18.04上，尝试安装气流。当我运行airflow initdb命令时，抛出以下错误
Traceback (most recent call last):
File "/home/uEnAFpip/.virtualenvs/airflow/bin/airflow", line 21, in <module>
from airflow import configuration
File "/home/uEnAFpip/.virtualenvs/airflow/lib/python3.6/site-packages/airflow/__init__.py", line 40, in <module>
from flask_admin import BaseView
File "/home/uEnAFpip/.virtualenvs/airflow/lib/python3.6/site-packages/flask_admin/__init__.py", line 6, in <module>
from .base import expose, expose_plugview, Admin, BaseView, AdminIndexView # noqa: F401
File "/home/uEnAFpip/.virtualenvs/airflow/lib/python3.6/site-packages/flask_admin/base.py", line 6, in <module>
from flask import Blueprint, current_app, render_template, abort, g, url_for
File "/home/uEnAFpip/.virtualenvs/airflow/lib/python3.6/site-packages/flask/__init__.py", line 20, in <module>
from .app import Flask
File "/home/uEnAFpip/.virtualenvs/airflow/lib/python3.6/site-packages/flask/app.py", line 69, in <module>
from .wrappers import …airflow ×1