Update ExchangeRate-API

ExchangeRate-API now requires an apiKey

README.md

@@ -247,7 +247,7 @@ API | Description | Auth | HTTPS | CORS |
 | [Currencylayer](https://currencylayer.com/documentation) | Exchange rates and currency conversion | `apiKey` | Yes | Unknown |
 | [CurrencyScoop](https://currencyscoop.com/api-documentation) | Real-time and historical currency rates JSON API | `apiKey` | Yes | Yes |
 | [Czech National Bank](https://www.cnb.cz/cs/financni_trhy/devizovy_trh/kurzy_devizoveho_trhu/denni_kurz.xml) | A collection of exchange rates | No | Yes | Unknown |
-| [ExchangeRate-API](https://www.exchangerate-api.com) | Free currency conversion | No | Yes | Yes |
+| [ExchangeRate-API](https://www.exchangerate-api.com) | Free currency conversion | `apiKey` | Yes | Yes |
 | [Exchangerate.host](https://exchangerate.host) | Free foreign exchange & crypto rates API | No | Yes | Unknown |
 | [Exchangeratesapi.io](https://exchangeratesapi.io) | Exchange rates with currency conversion | `apiKey` | Yes | Yes |
 | [Frankfurter](https://www.frankfurter.app/docs) | Exchange rates, currency conversion and time series | No | Yes | Yes |