ci: change hostname from `db` to `localhost` #433

Job	Run time
Build and test with Node.js 18 and postgresql	39s
Build and test with Node.js 18 and postgresql	47s
Build and test with Node.js 18 and postgresql	1m 37s
Build and test with Node.js 18 and mysql	48s
Build and test with Node.js 18 and mysql	57s
Build and test with Node.js 18 and mysql	55s
Build and test with Node.js 20 and postgresql	38s
Build and test with Node.js 20 and postgresql	42s
Build and test with Node.js 20 and postgresql	1m 24s
Build and test with Node.js 20 and mysql	44s
Build and test with Node.js 20 and mysql	49s
Build and test with Node.js 20 and mysql	43s
	10m 43s

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