Add PostgreSQL database support #2854

Job	Run time
softhsm2-test (1.79.0, hsm,hsm-tests-pkcs11)	2m 12s
pykmip-test (1.79.0, hsm)	2m 16s
softhsm2-test (stable, hsm,hsm-tests-pkcs11)	2m 27s
build (ubuntu-latest, 1.79.0, --no-default-features)	1m 53s
pykmip-test (1.79.0, hsm,hsm-tests-kmip)	2m 16s
softhsm2-test (beta, hsm,hsm-tests-pkcs11)	2m 30s
build (ubuntu-latest, 1.79.0)	1m 54s
pykmip-test (stable, hsm)	2m 17s
build (ubuntu-latest, 1.79.0, --features all)	1m 54s
pykmip-test (stable, hsm,hsm-tests-kmip)	2m 14s
build (ubuntu-latest, stable, --no-default-features)	1m 36s
pykmip-test (beta, hsm)	2m 2s
build (ubuntu-latest, stable)	1m 54s
pykmip-test (beta, hsm,hsm-tests-kmip)	2m 5s
build (ubuntu-latest, stable, --features all)	1m 53s
build (ubuntu-latest, beta, --no-default-features)	1m 53s
build (ubuntu-latest, beta)	1m 53s
build (ubuntu-latest, beta, --features all)	1m 54s
	37m 3s

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