Add full git history fetch to ci.yml

[dariusptrs]

@hofbi I forgot we need this so that git rev-list HEAD --count returns the correct commit number for \GitRevision. Thats why I had it initally in my previous PR.

[hofbi]

Is there another way to get the number of commits? Did it work before?

[dariusptrs]

We could replace the number with the commit SHA (optionally also again with a hyperlink to the commit) or maybe GitHub API offers an option to get the total number of commits.
Right now it always returns 1 as the commit number.

[hofbi]

The current option causes "0 indicates all history for all branches and tags.". We only need the full histroy of the main/master branch. If that it easy to configure let's do it. Else we can also go for this since we don't expect a huge histroy with many branches.

[dariusptrs]

I think its not that easily configurable. You could to something like git fetch --depth=1000000 which then is branch specific and will probably cause no problems. But it is more of a workaround...