Bump django-multifactor from 0.6.2 to 0.7.0 in /server (#106)

Bumps [django-multifactor](https://github.com/oliwarner/django-multifactor) from 0.6.2 to 0.7.0.
- [Release notes](https://github.com/oliwarner/django-multifactor/releases)
- [Commits](oliwarner/django-multifactor@v0.6.2...v0.7)

---
updated-dependencies:
- dependency-name: django-multifactor
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

server/requirements.txt

@@ -10,7 +10,7 @@ django-cors-headers==4.3.*
 django-decorator-include==3.0
 django-extensions==3.2.*
 django-formset-js-improved
-django-multifactor==0.6.2
+django-multifactor==0.7.0
 djangorestframework==3.15.*
 emoji==2.12.*
 icalendar==5.0.*