Is your feature request related to a problem? Please describe.

cloud.google.com/go/pubsub is deprecated. there is a new cloud.google.com/go/pubsub/v2

it is not possible to upgrade other libraries to v2 when some are still using v1.
this is due to loading of protos with same name

Describe the solution you'd like

Upgrade pubsub/gcppubsub to use cloud.google.com/go/pubsub/v2

Describe alternatives you've considered

N/A

Additional context

N/A