Fix docker push (#1601)
Summary:
Fix the github secret name used in the nightly docker build.
Test workflow:
https://github.com/pytorch/benchmark/actions/runs/4855836727
Pull Request resolved: https://github.com/pytorch/benchmark/pull/1601
Reviewed By: janeyx99
Differential Revision: D45463329
Pulled By: xuzhao9
fbshipit-source-id: 9f77c784aebfcc2febe641f648f11d2e6e4fbdf1
