Update cimg/postgres Docker tag to v18

[openssf-badge-renovate]

This PR contains the following updates:

Package	Type	Update	Change
cimg/postgres	docker	major	16.14 → 18.4

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (73db726) to head (0d4fa7d).

Additional details and impacted files

@@            Coverage Diff            @@
##              main     #2946   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           82        82           
  Lines         4576      4576           
=========================================
  Hits          4576      4576           

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