chore(deps): update postgres docker tag to v18

[renovate]

This PR contains the following updates:

Package	Type	Update	Change
postgres (source)	service	major	15-alpine → 18-alpine
postgres (source)		major	17 → 18
postgres (source)	docker	major	15 → 18

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 73.47%. Comparing base (3317684) to head (a3b325f).
⚠️ Report is 1143 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #434      +/-   ##
==========================================
- Coverage   73.48%   73.47%   -0.01%     
==========================================
  Files         268      268              
  Lines       30362    30362              
==========================================
- Hits        22310    22307       -3     
- Misses       8052     8055       +3     

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