Fix sbt-ghpages setup

[oguzhanunlu]

We are able to publish docs from local dev machine, where we have ssh access to the repository. However, when running on gh actions, the sbt-ghpages plugin can't clone the repository and update gh-pages branch, leading to an error like

[error] Cloning into '.'...
[error] git@github.com: Permission denied (publickey).
[error] fatal: Could not read from remote repository.
[error] Please make sure you have the correct access rights
[error] and the repository exists.
[error] Nonzero exit code (128) running git.
[error] (ghpagesUpdatedRepository) Nonzero exit code (128) running git.

Until this is fixed, we need to publish docs from dev machines using the following:

sbt "project docs" clean makeSite ghpagesPushSite

[istreeter]

Probably because this repo is still private (for now). We will need to make it publicly visible before we start using it in open source snowplow apps. So let's retry after we've made it public.