tests

test: add Postgres MCP tests #4664

Job	Run time
unit tests (3.13)	1m 3s
integration tests (macos-latest, 3.13)	1m 21s
integration tests (windows-latest, 3.9)	2m 3s
integration tests (ubuntu-latest, 3.9)	56s
integration tests (ubuntu-latest, 3.13)	1m 25s
integration tests (windows-latest, 3.13)	1m 45s
unit tests (3.9)	58s
integration tests (macos-latest, 3.9)	1m 36s
	11m 7s

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