switch to GitHub deployment for pages

[xsaschako]

Motivation / Current Behaviour

No third party libraries and lesser dependencies and code to manage

Enhancement description

switch to GitHub deployment for pages

Additional context

No response

Checklist

• [x] Attached labels, especially loc:: or model:: labels.
• [x] Linked to project

[reneSchm]

So I found the relevant documentation for setting up the deployment, but it also says that the action based publishing is still in beta. Since the branch based workflow works (again, as of yesterday), I think we should wait until there is a stable version.

[xsaschako]

Skimmed over that too, the workflow though looks easy enough so that it would be usable. But yes, as it isn't urgent I'd wait too.