update maintainers

[lahabana]

What happened?

This is out of date: https://github.com/kumahq/kuma/blob/master/OWNERS.md

We also need to update: https://github.com/cncf/foundation/blob/main/project-maintainers.csv at the same time.

Also then we need to: "after please submit a separate ServiceDesk ticket if the new maintainers have to be added to the ServiceDesk, mailing lists, etc."

We should document the process in the OWNERS or in GORVENANCE so it's let's of a mess

[lahabana]

Icarus to do the first update and then document the steps. Then everyone can do this for someone else.