USN-6414-2: Django vulnerabilities

USN-6414-1 and USN-6378-1 fixed CVE-2023-43665 and CVE-2023-41164 in Django, respectively. This update provides the corresponding update for Ubuntu 18.04 LTS. Original advisory details: Wenchao Li 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. It was discovered that Django incorrectly handled certain URIs with a very large number of Unicode characters. A remote attacker could possibly use this issue to cause Django to consume resources or crash, leading to a denial of service.