added ExtractIsoWeekDay (#912)

https://docs.djangoproject.com/en/3.2/ref/models/database-functions/#django.db.models.functions.ExtractIsoWeekDay

django-stubs/db/models/functions/__init__.pyi

@@ -6,6 +6,7 @@ from .comparison import NullIf as NullIf
 from .datetime import Extract as Extract
 from .datetime import ExtractDay as ExtractDay
 from .datetime import ExtractHour as ExtractHour
+from .datetime import ExtractIsoWeekDay as ExtractIsoWeekDay
 from .datetime import ExtractIsoYear as ExtractIsoYear
 from .datetime import ExtractMinute as ExtractMinute
 from .datetime import ExtractMonth as ExtractMonth

django-stubs/db/models/functions/datetime.pyi

@@ -20,6 +20,7 @@ class ExtractMonth(Extract): ...
 class ExtractDay(Extract): ...
 class ExtractWeek(Extract): ...
 class ExtractWeekDay(Extract): ...
+class ExtractIsoWeekDay(Extract): ...
 class ExtractQuarter(Extract): ...
 class ExtractHour(Extract): ...
 class ExtractMinute(Extract): ...