Update azure/durable_functions/models/DurableOrchestrationContext.py

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Author: AnatoliB

azure/durable_functions/models/DurableOrchestrationContext.py

@@ -763,13 +763,13 @@ def _get_function_name(self, name: FunctionBuilder,
             raise e
 
     @property
-    def version(self) -> str:
+    def version(self) -> Optional[str]:
         """Get the version assigned to the orchestration instance on creation.
 
         Returns
         -------
-        str
-            The version assigned to the orchestration instance on creation.
+        Optional[str]
+            The version assigned to the orchestration instance on creation, or None if not found.
         """
         return self._version