Avoid Django 3.2+ warning (#686)

postorius/mailman-web/settings.py

@@ -143,6 +143,11 @@ DATABASES = {
     'default': dj_database_url.config(conn_max_age=600)
 }
 
+# Avoid Django 3.2+ warning
+# https://github.com/maxking/docker-mailman/issues/595
+DEFAULT_AUTO_FIELD = 'django.db.models.AutoField'
+
+
 # If you're behind a proxy, use the X-Forwarded-Host header
 # See https://docs.djangoproject.com/en/1.8/ref/settings/#use-x-forwarded-host
 USE_X_FORWARDED_HOST = True