chore(deps): bump cloud.google.com/go/pubsub from 1.39.0 to 1.40.0 (#5786)

Bumps [cloud.google.com/go/pubsub](https://github.com/googleapis/google-cloud-go) from 1.39.0 to 1.40.0.
- [Release notes](https://github.com/googleapis/google-cloud-go/releases)
- [Changelog](https://github.com/googleapis/google-cloud-go/blob/main/CHANGES.md)
- [Commits](https://github.com/googleapis/google-cloud-go/compare/pubsub/v1.39.0...pubsub/v1.40.0)

---
updated-dependencies:
- dependency-name: cloud.google.com/go/pubsub
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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go.mod

@@ -4,7 +4,7 @@ go 1.22.0
 
 require (
 	cloud.google.com/go v0.115.0 // indirect
-	cloud.google.com/go/pubsub v1.39.0
+	cloud.google.com/go/pubsub v1.40.0
 	cloud.google.com/go/storage v1.42.0
 	github.com/Azure/azure-pipeline-go v0.2.3
 	github.com/Azure/azure-storage-blob-go v0.15.0