Update postgres Docker tag to v18

[renovate]

This PR contains the following updates:

Package	Type	Update	Change
postgres	service	major	17 -> 18
postgres		major	17 -> 18

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[github-actions]

Code Coverage Report: Only Changed Files listed

Package	Coverage
Overall Coverage	🟢 50.9%

Minimum allowed coverage is 0%, this run produced 50.9%