Add fix in migration to uniform TCCs

aleksis/apps/lesrooster/migrations/0018_uniform_tcc.py

@@ -14,11 +14,11 @@ def _create_tcc(apps, schema_editor):
                 Q(groups__school_term__pk=validity_range.school_term.pk) |
                 Q(groups__parent_groups__school_term__pk=validity_range.school_term.pk)
         ):
-            tcc = TimeboundCourseConfig.objects.create(
-                managed_by_app_label=TimeboundCourseConfig._meta.app_label,
+            tcc, __ = TimeboundCourseConfig.objects.update_or_create(
                 course=course,
                 validity_range=validity_range,
-                lesson_quota=course.lesson_quota,
+                defaults=dict(managed_by_app_label=TimeboundCourseConfig._meta.app_label,
+                lesson_quota=course.lesson_quota),
             )
             tcc.teachers.set(course.teachers.all())