Update kotlin to v0.8.0 (#2854)
* Update kotlin to v0.8.0
* Adapt our setup to `v0.8.0`'s changes
* Make sure verification tasks run on `check` tasks
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Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>
Co-authored-by: Jorge MartÃn <jorgem@element.io>