qapi/schema: Use super()

Commit 2cae67bcb5e (qapi: Use super() now we have Python 3) converted
the code to super().  Shortly after, commit f965e8fea6a (qapi: New
special feature flag "deprecated") neglected to use super().  Convert
it now.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20230316071325.492471-3-armbru@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
1 file changed