[CHANGE ME] Re-generated google-cloud-secret_manager-v1beta1 to pick up changes in the API or client library generator.

[yoshi-automation]

This PR was generated using Autosynth. 🌈

Commits in this repo since last synth:
76d8ae6 chore: Add billing veneer library
ede794c docs(secret_manager): change a few readme references from language to secret-manager
ec2f7de Release google-cloud-dataproc 0.8.0 (#4765)
3b2e9fb Release google-cloud-dialogflow 0.12.2 (#4769)
a1961b6 Release google-cloud-resource_manager 0.33.1 (#4764)
96d66e4 Release google-cloud-vision 0.37.3 (#4760)
0e07f61 Release google-cloud-pubsub 1.2.2 (#4757)
df839d2 Release google-cloud-monitoring 0.35.0 (#4756)
e476a04 Release google-cloud-asset 0.7.0 (#4752)
7c91648 Release google-cloud-video_intelligence 2.0.3 (#4746)

Log from Synthtool

synthtool > Executing /tmpfs/src/git/autosynth/working_repo/google-cloud-secret_manager-v1beta1/synth.py.
synthtool > Ensuring dependencies.
synthtool > Cloning googleapis.
synthtool > Pulling Docker image: gapic-generator-ruby:latest
latest: Pulling from gapic-images/gapic-generator-ruby
Digest: sha256:198a277e15f80282aff478995b9ddd970c2aa5a056ec2207b401cd6b28e8198f
Status: Image is up to date for gcr.io/gapic-images/gapic-generator-ruby:latest
synthtool > Generating code for: google/cloud/secrets/v1beta1.
synthtool > Generated code into /tmpfs/tmp/tmpwnxngfcd.
synthtool > Wrote metadata to synth.metadata.

[quartzmo]

refactor(secret_manager_v1beta1): Ensure top-level namespace ::Google::Protobuf