Package postgresdriver provides PostgreSQL-specific helpers for the database
layer.
It builds PostgreSQL data source name strings (defaulting sslmode to
"prefer") and creates upper/db query sessions from an existing *sql.DB
connection pool.
Build a data source name string. If sslmode is empty we fall back to "prefer"
— pgx rejects an empty value, and "prefer" is the safest default (tries SSL,
falls back to plain TCP if the server doesn't support it).