Switched to use jackc/pgx/v5 from lib/pq

[EHDoPfuH]

What changed?
Switched the driver used to connect to PostgreSQL

Why?
pgx has necessary features (HA etc.) and is compatible with sqlx used in SQL plugins

How did you test it?
Tests run

Potential risks
No risks.

Is hotfix candidate?
No

#1775

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