WebSocket api to set Volume (0-100) cannot handle multiple fast volume changes

[Joni-Salminen]

after couple successive volume changes, volume control stops working as intended.

This can be reproduced pretty easily.

1. Open web gui (or some client app which can adjust volume)
2. Open volume pane
3. Move slider and up down for sometime
4. stop the slider to about 50
5. move the slider to max volume
6. it stays at the max volume for moment, then jumps somewhere in between max and the value you stopped in step 4

I believe this has been issue on volumio2 allready(based on the complaints ive got for non working volume control), so it affects all the versions of volumio 3 aswell.

RPi 4, Usb Dac(Driverless), Volumio 3.163