on delete contact update issue (#14770)

* on delete contact update isuue

remove contact from issue if the deleted contact exists

* moved issue update function to issue.py

* Update formatting and comment

erpnext/hooks.py

@@ -210,6 +210,9 @@ doc_events = {
 	},
 	('Sales Invoice', 'Purchase Invoice', 'Delivery Note'): {
 		'validate': 'erpnext.regional.india.utils.set_place_of_supply'
+	},
+	"Contact":{
+		"on_trash": "erpnext.support.doctype.issue.issue.update_issue"
 	}
 }