Bump django from 3.1.4 to 3.1.8 in /requirements/base
Bump django from 3.1.4 to 3.1.8 in /requirements/base

Bumps [django](https://github.com/django/django) from 3.1.4 to 3.1.8.
- [Release notes](https://github.com/django/django/releases)
- [Commits](https://github.com/django/django/compare/3.1.4...3.1.8)

Signed-off-by: dependabot[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@github.com>
studentenportal/web,studentenportal/web,studentenportal/web,studentenportal/web,studentenportal/web