Update maintainers
Update maintainers

Fabian and Alex are not part of the team any more.

Signed-off-by: Babis Chalios <740f46968515b4d7c75446d3cf18612b4f944307@amazon.es>

firecracker-microvm/firecracker,firecracker-microvm/firecracker,firecracker-microvm/firecracker,firecracker-microvm/firecracker,firecracker-microvm/firecracker