Bump django-timezone-field from 5.1 to 6.1.0

Bumps [django-timezone-field](https://github.com/mfogel/django-timezone-field) from 5.1 to 6.1.0.
- [Commits](mfogel/django-timezone-field@5.1...6.1.0)

---
updated-dependencies:
- dependency-name: django-timezone-field
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

requirements/production.txt

@@ -8,7 +8,7 @@ django-crispy-forms==1.14.0
 django-model-utils==4.3.1
 django-multiselectfield==0.1.12
 django-taggit==1.2.0
-django-timezone-field==5.1
+django-timezone-field==6.1.0
 easy-thumbnails==2.8.5
 gunicorn==20.1.0
 lxml<5.0