MariaDB supports "INSERT ... RETURNING ..." since 10.5.0, so this patch makes `mysqlGetNextResourceIndex` use that, provided the query is run on MariaDB of a sufficient version. If it's not supported it proceeds as it always did.
Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/8691
Reviewed-by: Gusted <gusted@noreply.codeberg.org>
Co-authored-by: BtbN <btbn@btbn.de>
Co-committed-by: BtbN <btbn@btbn.de>