Publish nightly version to Docker Hub too

[dapplion]

Motivation

With #2647 we are releasing nightly versions to NPM. We should do the same for Docker Hub.

Description

Grab the tag from lerna's logic and publish to Docker Hub.

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[mpetrunic]

I think it would be wise to also change dockerfile to only install npm package otherwise we will spend huge amount of ci time just building that docker images

[dapplion]

I think it would be wise to also change dockerfile to only install npm package otherwise we will spend huge amount of ci time just building that docker images

Yeah I'm on it #2672

[dapplion]

Warning! There can be a race condition if NPM does not serve the recently pushed version immediately. The build should target the exact version of this nightly build.

We could use this API https://registry.npmjs.org/@chainsafe/lodestar-cli to ensure that our target nightly version is already available.