Fix linting (#594)

Author: andystaples

azure/durable_functions/models/DurableOrchestrationContext.py

@@ -248,7 +248,7 @@ def call_http(self, method: str, uri: str, content: Optional[str] = None,
             The HTTP request uri.
         content: str or dict, optional
             The HTTP request content. Can be a string or a JSON-serializable dictionary.
-            Note: Although the type hint says 'str', a dictionary is accepted 
+            Note: Although the type hint says 'str', a dictionary is accepted
             and will be serialized to JSON.
         headers: Optional[Dict[str, str]]
             The HTTP request headers.