tests

test: add Postgres MCP tests #4666

Job	Run time
unit tests (3.13)	1m 2s
integration tests (windows-latest, 3.13)	2m 5s
integration tests (macos-latest, 3.9)	1m 36s
unit tests (3.9)	1m 1s
integration tests (ubuntu-latest, 3.13)	51s
integration tests (macos-latest, 3.13)	1m 25s
integration tests (ubuntu-latest, 3.9)	59s
integration tests (windows-latest, 3.9)	1m 31s
	10m 30s

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