Description
There is a bug in the Validate function for py3 validator.
https://github.com/apache/avro/blob/master/lang/py3/avro/io.py#L149
The `AvroTypeException` will fail (if ever reached), because the exception accepts two arguments: `expected_schema, datum`.
This issue was found here: https://github.com/apache/avro/pull/516/files#r287870842 and might be as well fixed in AVRO-2413.