fix: SyntaxWarning for 'return' in a 'finally' block on Python 3.14

Author: jonathan343

packages/smithy-aws-event-stream/src/smithy_aws_event_stream/_private/serializers.py

@@ -59,10 +59,8 @@ def begin_struct(self, schema: "Schema") -> Iterator[ShapeSerializer]:
         # Note that if we're serializing an operation input or output, it won't be a
         # union at all, so this won't get triggered. Thankfully, that's what we want.
         if schema.shape_type is ShapeType.UNION:
-            try:
-                yield self
-            finally:
-                return
+            yield self
+            return
 
         headers: dict[str, HEADER_VALUE] = {}