fix: exchange rate not fetching correctly (#20010)

diff --git a/erpnext/accounts/doctype/journal_entry/journal_entry.py b/erpnext/accounts/doctype/journal_entry/journal_entry.py
index e25942c..8897337 100644
--- a/erpnext/accounts/doctype/journal_entry/journal_entry.py
+++ b/erpnext/accounts/doctype/journal_entry/journal_entry.py
@@ -968,7 +968,7 @@
 
 		# The date used to retreive the exchange rate here is the date passed
 		# in as an argument to this function.
-		elif (not exchange_rate or exchange_rate==1) and account_currency and posting_date:
+		elif (not exchange_rate or flt(exchange_rate)==1) and account_currency and posting_date:
 			exchange_rate = get_exchange_rate(account_currency, company_currency, posting_date)
 	else:
 		exchange_rate = 1