pubsub: deprecate Done
pubsub: deprecate Done

Change-Id: Id96879ee6699c19d6c7793782ef26afc3a3cf8e3
Reviewed-on: https://code-review.googlesource.com/8470
Reviewed-by: Michael Darakananda <176c4818757ce942f02114959cee75d35f2575d9@google.com>
Reviewed-by: Ross Light <dfccc06f14414bff5a59be7fc90abf4404b47fc8@google.com>

michael-grosshans/google-cloud-go,googleapis/google-cloud-go,michael-grosshans/google-cloud-go,googleapis/google-cloud-go,googleapis/google-cloud-go,googleapis/google-cloud-go