fix: add labels for translation in purchase_order_analysis.py

(cherry picked from commit 342a398)

erpnext/buying/report/purchase_order_analysis/purchase_order_analysis.py

@@ -180,7 +180,7 @@ def prepare_data(data, filters):
 
 
 def prepare_chart_data(pending, completed):
-	labels = ["Amount to Bill", "Billed Amount"]
+	labels = [_("Amount to Bill"), _("Billed Amount")]
 
 	return {
 		"data": {"labels": labels, "datasets": [{"values": [pending, completed]}]},