fix: cover case when all material needs to be bought (#29326)

When material request is to be made for purchase qty should be converted
to purchase UOM
diff --git a/erpnext/manufacturing/doctype/production_plan/production_plan.py b/erpnext/manufacturing/doctype/production_plan/production_plan.py
index 4d31f41..19a0694 100644
--- a/erpnext/manufacturing/doctype/production_plan/production_plan.py
+++ b/erpnext/manufacturing/doctype/production_plan/production_plan.py
@@ -947,10 +947,6 @@
 	locations = get_available_item_locations(item.get("item_code"),
 		warehouses, item.get("quantity"), company, ignore_validation=True)
 
-	if not locations:
-		new_mr_items.append(item)
-		return
-
 	required_qty = item.get("quantity")
 	for d in locations:
 		if required_qty <=0: return
@@ -970,8 +966,8 @@
 
 	if required_qty:
 		stock_uom, purchase_uom = frappe.db.get_value(
-			'Item', 
-			item['item_code'], 
+			'Item',
+			item['item_code'],
 			['stock_uom', 'purchase_uom']
 		)