Bug#1058532: golang-google-api: FTBFS: tests failed

[M Hickford]

> --- FAIL: TestTokenSource (0.00s)
> panic: cannot handle unexported field at {*google.Credentials}.universeDomain:
> "golang.org/x/oauth2/google".Credentials

This is fixed upstream
https://github.com/googleapis/google-api-go-client/commit/b3a71bda027d9ff92df3bf76b5ee9ffa55520dd9
so hopefully updating the package would fix the problem