Dockerfile: use alphine for the final image

[ilgooz]

instead of https://github.com/tendermint/starport/blob/54f9bae/Dockerfile#L37

[lumtis]

Wasn't Alpine less optimized than the current one we use?

[ilgooz]

What do you mean by less optimized?

[faddat]

Probably less tiny.

I eschew alpine these days because of musl.

Thus far, my solution has been home-brewed, an arm64/amd64 arch image called

faddat/archlinux

Github actions updates it once every 24 hours. No musl trouble with it, but it is not hyper-minimal the way that the default ubuntu image is, let alone alpine or base or distroless.