Change default debounce to 250ms

[sandyjmacdonald]

I'm getting double-clicks with the debounce at 150ms, but 250ms seems to eliminate this.

[Gadgetoid]

Done! Will have to update https://github.com/pimoroni/pirate-audio/blob/master/mopidy/install.sh separately, since those values are hard-coded in the config-a-majig.