Update gitlab runnner to Windows 11

Currently, we are having a windows GitLab runner with Windows 10 installed. This runner executes a build and a test job based on the MSVC compiler directly on the windows host system.

As Windows 11 was released one year ago and most of our windows developers switched to it, we could consider also moving the Windows 10 runner to Windows 11.

Any opinions on that? @m.schoenherr @k.kutscher @a.wellmann