[DOP-13849] - upgrade Postgres packages

[maxim-lixakov]

Change Summary

• Postgres connection now uses PostgreSQL JDBC driver 42.7.3, upgraded from 42.6.0, and supports passing custom versions: Postgres.get_packages(package_version=...).
• Update following tests and documentation

Related issue number

Checklist

• Commit message and PR title is comprehensive
• Keep the change as small as possible
• Unit and integration tests for the changes exist
• Tests pass on CI and coverage does not decrease
• Documentation reflects the changes where applicable
• docs/changelog/next_release/<pull request or issue id>.<change type>.rst file added describing change
  (see CONTRIBUTING.rst for details.)
• My PR is ready to review.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 94.40%. Comparing base (78bad0a) to head (c0f314c).

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #251      +/-   ##
===========================================
+ Coverage    94.38%   94.40%   +0.01%     
===========================================
  Files          204      204              
  Lines         7892     7897       +5     
  Branches      1403     1403              
===========================================
+ Hits          7449     7455       +6     
+ Misses         318      317       -1     
  Partials       125      125              

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