Same Game example: prevent window resize

In the same game example ( https://doc.qt.io/qt-6/qtdoc-demos-samegame-example.html ) the window resize works, but is not sensible and should be disabled.

e.g. the "Puzzles" mode 1st stage (clear in 3 moves) is impossible to pass, if the UI is in fullscreen:

It

Small improvement, I know, but currently the end-user gets wrong understanding of the example if they run it on fullscreen.