fix(HR): Permission error while adding weekly holidays (#25450)

diff --git a/erpnext/hr/doctype/holiday_list/holiday_list.py b/erpnext/hr/doctype/holiday_list/holiday_list.py
index 6df7bc8..67630a0 100644
--- a/erpnext/hr/doctype/holiday_list/holiday_list.py
+++ b/erpnext/hr/doctype/holiday_list/holiday_list.py
@@ -16,6 +16,7 @@
 		self.validate_days()
 		self.total_holidays = len(self.holidays)
 
+	@frappe.whitelist()
 	def get_weekly_off_dates(self):
 		self.validate_values()
 		date_list = self.get_weekly_off_date_list(self.from_date, self.to_date)