Fix CDK speedrun stream stub (airbytehq#5778)

* Fix CDK speedrun stream stub

* Add start_date back

Co-authored-by: Abhi Vaidyanatha <abhivaidyanatha@Abhis-MacBook-Pro.local>

docs/connector-development/tutorials/cdk-speedrun.md

@@ -90,8 +90,13 @@ class SourcePythonHttpExample(AbstractSource):
             return True, None
 
     def streams(self, config: Mapping[str, Any]) -> List[Stream]:
-        # Parse the date from a string into a datetime object
+        # Parse the date from a string into a datetime object.
         start_date = datetime.strptime(config["start_date"], "%Y-%m-%d")
+
+        # NoAuth just means there is no authentication required for this API and is included for completeness.
+        # Skip passing an authenticator if no authentication is required.
+        # Other authenticators are available for API token-based auth and Oauth2. 
+        auth = NoAuth()
         return [ExchangeRates(authenticator=auth, base=config["base"], start_date=start_date)]
 ```