fix(set_message): encode strings if field is bytes

Author: russkel

rosidl_runtime_py/set_message.py

@@ -70,6 +70,8 @@ def set_message_fields_internal(
                 value = numpy.array(field_value, dtype=field.dtype)
             elif type(field_value) is field_type:
                 value = field_value
+            elif field_type is bytes and type(field_value) is str:
+                value = field_value.encode()
             # We can't import these types directly, so we use the qualified class name to
             # distinguish them from other fields
             elif qualified_class_name == 'std_msgs.msg._header.Header' and \