Bump django-auth-ldap from 1.4.0 to 2.2.0 in /cvat/requirements (#1739)

Bumps [django-auth-ldap](https://github.com/django-auth-ldap/django-auth-ldap) from 1.4.0 to 2.2.0.
- [Release notes](https://github.com/django-auth-ldap/django-auth-ldap/releases)
- [Changelog](https://github.com/django-auth-ldap/django-auth-ldap/blob/master/CHANGES)
- [Commits](https://github.com/django-auth-ldap/django-auth-ldap/compare/1.4.0...2.2.0)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

cvat/requirements/base.txt

@@ -1,7 +1,7 @@
 click==6.7
 Django==2.2.13
 django-appconf==1.0.4
-django-auth-ldap==1.4.0
+django-auth-ldap==2.2.0
 django-cacheops==5.0
 django-compressor==2.4
 django-rq==2.0.0