pip:Could not install packages due to an OSError: HTTPSConnectionPool
ERROR: Could not install packages due to an OSError: HTTPSConnectionPool(host='files.pythonhosted
.org', port=443): Max retries exceeded with url: /packages/b0/3a/88b210db68e56854d0bcf4b38e165e03
be377e13907746f825790f3df5bf/setuptools-59.6.0-py3-none-any.whl (Caused by ConnectTimeoutError(<p
ip._vendor.urllib3.connection.HTTPSConnection object at 0x0000014E865360B8>, 'Connection to files.pythonhosted.org timed out. (connect timeout=15)'))
原因：
pip 下载速度太慢了
解决方法:从另一个源中下载
pip install xxx -i https://pypi.douban.com/simple/