fix(postgresql_metrics source): Support PG17 #48199

Job	Run time
changes / source	6s
changes / e2e_tests	0s
changes / int_tests	0s
Check version	1m 41s
Check scripts	1m 34s
Check events	1m 8s
Check clippy	8m 17s
Unit and Component Validation tests - x86_64-unknown-linux-gnu	19m 57s
Check code format	2m 4s
Check Rust Docs	6m 13s
VRL - Linux	3m 43s
Build VRL Playground	3m 25s
Check Cue docs	3m 35s
Check Component Docs	16m 30s
Check that the 3rd-party license file is up to date	0s
Check Markdown	1m 34s
Test Suite	3s
	1h 9m 50s

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