Add Postgress Logger tests

[treyburn]

• Brought in https://github.com/DATA-DOG/go-sqlmock for unit testing the postgres logger
• Found a couple minor bugs in verifyTableExists()
  • NULL result handling
  • defered rows.Close() on a nil row
• Realized the Close() method didn't close the db connection. Fixed that as well.

[codecov]

Codecov Report

❌ Patch coverage is 89.47368% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 59.25%. Comparing base (6aa1a3e) to head (3f7f42c).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
internal/pkg/logger/postgres.go	89.47%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##             main      #20       +/-   ##
===========================================
+ Coverage   33.07%   59.25%   +26.17%     
===========================================
  Files           5        5               
  Lines         263      270        +7     
===========================================
+ Hits           87      160       +73     
+ Misses        173      103       -70     
- Partials        3        7        +4     

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