解决：pip is configured with locations that require TLS/SSL

在使用pip进行软件包安装的时候出现问题：

WARNING: pip is configured with locations that require TLS/SSL, however the ssl module in Python is not available.
解决：

mkdir -p ~/.pip
vim ~/.pip/pip.conf

然后输入内容：

[global]
index-url = http://mirrors.aliyun.com/pypi/simple/

[install]
trusted-host = mirrors.aliyun.com

再次使用pip安装即可。