[postgresqlreceiver] bump supported PG version to 12 (#35898) #17346

Job	Run time
arm-unittest-matrix (receiver-0)	5m 14s
arm-unittest-matrix (receiver-1)	7m 12s
arm-unittest-matrix (receiver-2)	8m 47s
arm-unittest-matrix (receiver-3)	6m 16s
arm-unittest-matrix (processor-0)	3m 47s
arm-unittest-matrix (processor-1)	4m 33s
arm-unittest-matrix (exporter-0)	3m 36s
arm-unittest-matrix (exporter-1)	9m 43s
arm-unittest-matrix (exporter-2)	4m 20s
arm-unittest-matrix (exporter-3)	5m 3s
arm-unittest-matrix (extension)	6m 21s
arm-unittest-matrix (connector)	4m 2s
arm-unittest-matrix (internal)	6m 17s
arm-unittest-matrix (pkg)	3m 36s
arm-unittest-matrix (cmd-0)	1m 21s
arm-unittest-matrix (cmd-1)	1m 58s
arm-unittest-matrix (other)	4m 17s
arm-unittest	1s
	1h 26m 24s

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