Prepare release of Spark 0.3.4 and RCSSServer3D 0.7.5
As discussed previously with @StefanGlaser, a new release seems to make a lot of sense right now as more and more people have Ruby 3.x installed and can't run a multithreaded simulation anymore. Also, supporting ARM is getting increasingly important for running RCSSServer3D on the new Apple Silicon processors.
With that being said, this serves as a little reminder. Also, it may reduce the time required for making the release ;) (at least if I didn't screw up the content of this merge request...)