build(deps): update psycopg[binary] requirement (GoogleCloudPlatform#3289)

Updates the requirements on [psycopg[binary]](https://github.com/psycopg/psycopg) to permit the latest version.
- [Changelog](https://github.com/psycopg/psycopg/blob/master/docs/news.rst)
- [Commits](psycopg/psycopg@3.2.7...3.2.8)

---
updated-dependencies:
- dependency-name: psycopg[binary]
  dependency-version: 3.2.8
  dependency-type: direct:production
...

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samples/python/psycopg3/requirements.txt

@@ -1,4 +1,4 @@
-psycopg[binary]~=3.2.7
+psycopg[binary]~=3.2.8
 testcontainers~=4.10.0
 requests==2.32.3
 google~=3.0.0