Bump django-treebeard from 4.3.1 to 4.4

Bumps [django-treebeard](https://github.com/django-treebeard/django-treebeard) from 4.3.1 to 4.4.
- [Release notes](https://github.com/django-treebeard/django-treebeard/releases)
- [Changelog](https://github.com/django-treebeard/django-treebeard/blob/master/CHANGES.md)
- [Commits](django-treebeard/django-treebeard@4.3.1...4.4)

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

requirements.txt

@@ -39,7 +39,7 @@ django-taggit==1.3.0
 django-markdownify==0.8.1
 django-mptt==0.11.0
 django-modeltranslation>=0.11,<0.17.0
-django-treebeard==4.3.1
+django-treebeard==4.4
 django-guardian<2.3.1
 django-downloadview==2.1.1
 django-polymorphic==3.0.0