allow protobuf v4 ?

[asottile-sentry]

it looks like some of the google- libraries have started to allow protobuf 4.x but not all of them:

  protobuf<4.0.0dev,>=3.19.0 (from google-cloud-functions==1.8.0->-r /home/asottile/workspace/sentry/requirements-base.txt (line 25))
  protobuf<4.0.0dev,>=3.19.0 (from google-cloud-bigtable==2.11.1->-r /home/asottile/workspace/sentry/requirements-base.txt (line 20))
  protobuf<4.0.0dev,>=3.19.0 (from google-cloud-pubsub==2.13.4->-r /home/asottile/workspace/sentry/requirements-base.txt (line 23))

[unforced]

These are all getting merged in now, #207 should fix this and there should be a release shortly after that includes it.