Log Message:
py-google-auth: update to 1.7.0.

v1.7.0

Implementation Changes

    Add retry loop for fetching authentication token if any 'Internal Failure' \ 
occurs (#368)
    Use cls parameter instead of class (#341)

New Features

    Add support for impersonated_credentials.Sign, IDToken (#348)
    Add downscoping to OAuth2 credentials (#309)

Dependencies

    Update dependency cachetools to v3 (#357)
    Update dependency rsa to v4 (#358)
    Set an upper bound on dependencies version (#352)
    Require a minimum version of setuptools (#322)

Documentation

    Add busunkim96 as maintainer (#373)
    Update user-guide.rst (#337)
    Fix typo in jwt docs (#332)
    Clarify which SA has Token Creator role (#330)

Internal / Testing Changes

    Change 'name' to distribution name (#379)
    Fix system tests, move to Kokoro (#372)
    Blacken (#375)
    Rename nox.py -> noxfile.py (#369)
    Add initial renovate config (#356)
    Use new pytest api to keep building with pytest 5 (#353)