fix: purchase receipt to purchase invoice bill date mapping (#23967)

Co-authored-by: pateljannat <jannatpatel@MacBook-Air.local>
diff --git a/erpnext/stock/doctype/purchase_receipt/purchase_receipt.py b/erpnext/stock/doctype/purchase_receipt/purchase_receipt.py
index d964669..2cc4679 100644
--- a/erpnext/stock/doctype/purchase_receipt/purchase_receipt.py
+++ b/erpnext/stock/doctype/purchase_receipt/purchase_receipt.py
@@ -572,7 +572,8 @@
 			"doctype": "Purchase Invoice",
 			"field_map": {
 				"supplier_warehouse":"supplier_warehouse",
-				"is_return": "is_return"
+				"is_return": "is_return",
+				"bill_date": "bill_date"
 			},
 			"validation": {
 				"docstatus": ["=", 1],