chore: close postgres db on cleanup

[atzoum]

Description

Closing postgres sql.DB on cleanup to avoid resource leaks (debugging unexpected EOF errors in gha)

Security

• The code changed/added as part of this pull request won't create any security issues with how the software is being used.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 78.82%. Comparing base (a9420ee) to head (d5aef5c).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #357      +/-   ##
==========================================
- Coverage   79.65%   78.82%   -0.83%     
==========================================
  Files          91       82       -9     
  Lines        6788     6461     -327     
==========================================
- Hits         5407     5093     -314     
- Misses       1110     1116       +6     
+ Partials      271      252      -19     

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