Bump google-cloud-pubsub to 2.9.0 (to bump grpcio)

[allenporter]

Proposed change

The primary motivation is to kick off building wheels for grpcio, however there are also many pub/sub related bug fixes since 2.1.0 in September 2020.

googleapis/python-pubsub@v2.1.0...v2.9.0 where notable changes include Graceful streaming pull shutdown (desired by nest and should help with #63206) and flow control improvements.

This also implicitly pulls in GRPC, which has been behind since Aug 2020.
grpc/grpc@v1.31.0...v1.43.0

I've manually tested this with:

• Publisher client: Tested via google_pubsub
• Subscriber client: Tested via nest
• I've been using latest versions of grpcio for local development testing of google-nest-sdm for the past year

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
• New integration (thank you!)
• New feature (which adds functionality to an existing integration)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests

Additional information

• This PR fixes or closes issue:
  • fixes Nest integration fails to load first time in a new venv #55883
  • fixes Unable to upgrade grpcio to newer versions due to armv7 link error #56669
  • fixes Nest Integration is failing API and killing HA for 10mins #59516
• This PR is related to issue:
• Link to documentation pull request:

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[allenporter]

Separately, I'd like to figure out the best way for us to pin grpcio to a specific version, since its such a beast. I would like to manage it explicitly, though no integration directly depends on it. Edit: Any input on the best way to do that would be appreciated. Naive idea: I can just stick it on nest.

[frenck]

Here we go 🙏

Thanks @allenporter 👍

[frenck]

Any input on the best way to do that would be appreciated. Naive idea: I can just stick it on nest.

Let merge this, let see what it picks and if it works; pin that in our constraint to start with 👍