[caffe2] Properly call super init in schema.py (#47542)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/47542
The previous way of doing `Field.__init__(self, [])` is just wrong. Switching to Python2 compatible way: `super(ObjectName, self).__init__(...)`
Reviewed By: dzhulgakov
Differential Revision: D24771077
fbshipit-source-id: d6798c72090c0264b6c583602cae441a1b14587c
