Release version of eslint configs that support `eslint@9`

[sndrs]

v9 is a big change that requires the use of a new config format, and while compatibility tools have been released, it's not trivial to upgrade while the configs you rely on have not upgraded.

this makes it hard for us to upgrade ours, but obviously us not adding support it makes it hard for teams to upgrade too.

we should just bite the bullet, do a major release of the configs and only support v9 from now on.

they don't change v often so it should be ok (and the new config format will enable us to work on #1439)