Need fix after amphp/sql update

[deadbeat88]

After commit e257237b61da7cb25a59a95299e232e9b536d93c (Improve naming) at amphp/sql package need to fix Amp\Postgres\Connection class.

Fatal error: Class Amp\Postgres\PgSqlConnection contains 2 abstract methods and must therefore be declared abstract or implement the remaining methods (Amp\Sql\Link::beginTransaction, Amp\Sql\TransientResource::getLastUsedAt) in vendor/amphp/postgres/src/PgSqlConnection.php on line 14

[kelunik]

Yes, there have been a few renames. Would you like to provide a PR?

[deadbeat88]

Ok, I can to provide PR, but later...maybe tommorow at leisure time)