PHP 8.x Deprecation in postgres driver

Should probably use `get_resource_id` there (maybe with a polyfill because the function was introduced in PHP 8.0)

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[phpBB Debug] "Object of class PgSql\Result could not be converted to int" in file /var/www/phpbb/phpbb/db/driver/postgres.php on line 354
[phpBB Debug] "Object of class PgSql\Result could not be converted to int" in file /var/www/phpbb/phpbb/db/driver/postgres.php on line 356
[phpBB Debug] "Object of class PgSql\Result could not be converted to int" in file /var/www/phpbb/phpbb/db/driver/postgres.php on line 354