USN-6674-2: Django vulnerability

USN-6674-1 fixed a vulnerability in Django. This update provides
the corresponding update for Ubuntu 18.04 LTS.

Original advisory details:

Seokchan Yoon discovered that the Django Truncator function incorrectly
handled very long HTML input. A remote attacker could possibly use this
issue to cause Django to consume resources, leading to a denial of service.

advisory attacker denial of service django function html input issue lts resources service ubuntu update usn vulnerability yoon