fixup! fix(bulk-import): lookup custom object via slug

Author: anshulkamath

netbox_custom_objects/migrations/0002_customobjecttype_netbox_custom_objects_customobjecttype_slug.py

@@ -209,13 +209,6 @@ class Meta:
                     "A Custom Object Type with this name already exists."
                 ),
             ),
-            models.UniqueConstraint(
-                Lower("slug"),
-                name="%(app_label)s_%(class)s_slug",
-                violation_error_message=_(
-                    "A Custom Object Type with this slug already exists."
-                ),
-            ),
         ]
 
     def __str__(self):