fix: Return fieldtype so that the client-side can format chart values (#18211)

diff --git a/erpnext/accounts/report/profit_and_loss_statement/profit_and_loss_statement.py b/erpnext/accounts/report/profit_and_loss_statement/profit_and_loss_statement.py
index 48d7361..ac11868 100644
--- a/erpnext/accounts/report/profit_and_loss_statement/profit_and_loss_statement.py
+++ b/erpnext/accounts/report/profit_and_loss_statement/profit_and_loss_statement.py
@@ -93,4 +93,6 @@
 	else:
 		chart["type"] = "line"
 
+	chart["fieldtype"] = "Currency"
+
 	return chart
\ No newline at end of file