Comment 4 for bug 1907290

The same issue as below link
https://stackoverflow.com/questions/55657752/django-installing-mysqlclient-error-mysqlclient-1-3-13-or-newer-is-required

We are using pymysql instead of mysqlclient, right?
However, 0.9.3 is just the latest version of pymysql.
Now, it report below error, refer to
https://bugs.launchpad.net/starlingx/+bug/1908117/comments/3
django.core.exceptions.ImproperlyConfigured: mysqlclient 1.3.13 or newer is required; you have 0.9.3
We could not upgrade pymysql, that's why we lock down django to 2.1.5 version during ussuri upgrade.

Thanks!
Zhipeng