tests

test: add Postgres MCP tests #4665

Job	Run time
unit tests (3.13)	1m 12s
unit tests (3.9)	1m 4s
integration tests (ubuntu-latest, 3.9)	55s
integration tests (macos-latest, 3.9)	1m 49s
integration tests (macos-latest, 3.13)	1m 32s
integration tests (ubuntu-latest, 3.13)	1m 33s
integration tests (windows-latest, 3.13)	1m 52s
integration tests (windows-latest, 3.9)	1m 30s
	11m 27s

Provide feedback