[deps] Update django-taggit requirement from ~=4.0.0 to ~=6.1.0

Updates the requirements on [django-taggit](https://github.com/jazzband/django-taggit) to permit the latest version.
- [Changelog](https://github.com/jazzband/django-taggit/blob/master/CHANGELOG.rst)
- [Commits](jazzband/django-taggit@4.0.0...6.1.0)

---
updated-dependencies:
- dependency-name: django-taggit
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

requirements.txt

@@ -1,6 +1,6 @@
 django-sortedm2m~=3.1.1
 django-reversion~=5.1.0
-django-taggit~=4.0.0
+django-taggit~=6.1.0
 netjsonconfig @ https://github.com/openwisp/netjsonconfig/tarball/master
 django-x509~=1.2.0
 django-loci~=1.1.0