PR1045 [py3] Bump django from 1.11.20 to 1.11.28 in /desktop/core (#1045)
Bumps [django](https://github.com/django/django) from 1.11.20 to 1.11.28.
- [Release notes](https://github.com/django/django/releases)
- [Commits](https://github.com/django/django/compare/1.11.20...1.11.28)
Signed-off-by: dependabot[bot] <support@github.com>