Wallpaper configuration not applying since Plasma 6.6

Similar to #577, the `programs.plasma.workspace.wallpaper` attribute hasn't been applying since I upgraded my system to Plasma 6.6 (i.e. I now have the default wallpaper instead of the one I want). The lock screen works just fine though, despite it being set as `programs.plasma.kscreenlocker.appearance.wallpaper = config.programs.plasma.workspace.wallpaper;`, so it's definitely not an issue with the path of the former being incorrect.