[psycopg2] Bump to 2.9.12 (#15658)

Author: github-actions[bot]

stubs/psycopg2/METADATA.toml

@@ -1,3 +1,3 @@
-version = "2.9.11"
+version = "2.9.12"
 upstream-repository = "https://github.com/psycopg/psycopg2"
 partial-stub = false