Merge #1275 (update django-model-utils to 4.3.1)

Author: martey

requirements/production.txt

@@ -5,7 +5,7 @@ django-anymail[postmark]==8.6
 django-autoslug==1.9.8
 django-constance[redis]==2.9.1
 django-crispy-forms==1.14.0
-django-model-utils==4.2.0
+django-model-utils==4.3.1
 django-multiselectfield==0.1.12
 django-taggit==1.2.0
 django-timezone-field==4.2.3