chore: Test with latest postgres (18)

[tvdeyen]

Summary

We were testing with 13, which is already EOL. We want to be sure that we do not get any regressions with newer postgres versions, so we should test with latest all the time

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 92.16%. Comparing base (4697059) to head (78f96a8).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #6539   +/-   ##
=======================================
  Coverage   92.16%   92.16%           
=======================================
  Files        1036     1036           
  Lines       21188    21188           
=======================================
  Hits        19527    19527           
  Misses       1661     1661           

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