Bump google-cloud-secret-manager from 2.19.0 to 2.20.0

Bumps [google-cloud-secret-manager](https://github.com/googleapis/google-cloud-python) from 2.19.0 to 2.20.0.
- [Release notes](https://github.com/googleapis/google-cloud-python/releases)
- [Changelog](https://github.com/googleapis/google-cloud-python/blob/main/packages/google-cloud-documentai/CHANGELOG.md)
- [Commits](googleapis/google-cloud-python@google-cloud-secret-manager-v2.19.0...google-cloud-secret-manager-v2.20.0)

---
updated-dependencies:
- dependency-name: google-cloud-secret-manager
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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Author: dependabot[bot]

requirements.txt

@@ -1,4 +1,4 @@
 Flask==3.0.3
 Flask-HTTPAuth==4.8.0
 appengine-python-standard>=1.0.0
-google-cloud-secret-manager==2.19.0
+google-cloud-secret-manager==2.20.0