feat: Increase number of supported currency exchanges

Switch from frankfurter.app to exchange rate.host to accommodate more currency usage.
diff --git a/erpnext/setup/utils.py b/erpnext/setup/utils.py
index 13269a8..33af286 100644
--- a/erpnext/setup/utils.py
+++ b/erpnext/setup/utils.py
@@ -93,21 +93,21 @@
 
 	try:
 		cache = frappe.cache()
-		key = "currency_exchange_rate_{0}:{1}:{2}".format(transaction_date,from_currency, to_currency)
+		key = "currency_exchange_rate_{0}:{1}:{2}".format(transaction_date, from_currency, to_currency)
 		value = cache.get(key)
 
 		if not value:
 			import requests
-			api_url = "https://frankfurter.app/{0}".format(transaction_date)
+			api_url = "https://api.exchangerate.host/convert"
 			response = requests.get(api_url, params={
-				"base": from_currency,
-				"symbols": to_currency
+				"date": transaction_date,
+				"from": from_currency,
+				"to": to_currency
 			})
 			# expire in 6 hours
 			response.raise_for_status()
-			value = response.json()["rates"][to_currency]
-
-			cache.set_value(key, value, expires_in_sec=6 * 60 * 60)
+			value = response.json()["result"]
+			cache.setex(key, value, 6 * 60 * 60)
 		return flt(value)
 	except:
 		frappe.log_error(title="Get Exchange Rate")