✔ Fix sluggish rendering in #qutebrowser following #qt upgrade from 6.6.3 to 6.7
Problem: qt.force.software_rendering was set to "qt-quick"
Solution: Set qt.force.software_rendering to "none"
Story: Trying to watch Netflix (People Just Do Nothing) after the upgrade, qutebrowser played the video at a low framerate, lagging behind the audio which it played fine. Smooth scrolling was also choppy. Falkon, another qt-webengine browser, handled it all fine. Downgrading qt to 6.6.3 worked around it.
