Add pg 16 to CI and remove `:generic` explain plan option #1589

Job	Run time
unittest (1.15.6, 24.3.4.13)	19s
mssql integration test (1.11.4-erlang-21.3.8.24-alpine-3.13.3, 2017)	1m 36s
mysql integration test (1.11.4-erlang-21.3.8.24-alpine-3.13.3, 5.7)	1m 44s
mssql integration test (1.11.4-erlang-21.3.8.24-alpine-3.13.3, 2019)	1m 45s
postgres integration test (1.11.4-erlang-21.3.8.24-alpine-3.13.3, 16.2-alpine)	1m 22s
mysql integration test (1.11.4-erlang-21.3.8.24-alpine-3.13.3, 8.0)	1m 49s
postgres integration test (1.11.4-erlang-21.3.8.24-alpine-3.13.3, 11.11-alpine)	1m 19s
postgres integration test (1.11.4-erlang-21.3.8.24-alpine-3.13.3, 9.6-alpine)	1m 14s
postgres integration test (1.11.4-erlang-21.3.8.24-alpine-3.13.3, 9.5-alpine)	1m 12s
unittest (1.15.6, 26.1.2, lint)	21s
	12m 41s

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