[JIT] fix py35 test (#34350)
Summary:
test_module_interfaces was using syntax only supported in >= 3.6
Pull Request resolved: https://github.com/pytorch/pytorch/pull/34350
Reviewed By: mrshenli
Differential Revision: D20298869
Pulled By: eellison
fbshipit-source-id: 22319ca403113cff2eedf57767bb34d9580e6db3
