Add volume synchronization framework

Add volume synchronization functionality to spotify streams

Author: SteveMicroNova

CHANGELOG.md

@@ -4,7 +4,6 @@
 * System
   * Upgraded volume calculations to preserve relative positions when hitting the min or max setting via source volume bar
   * Update our spotify provider `go-librespot` to `0.7.3`
-  * Upgraded volume calculations to preserve relative positions when hitting the min or max setting via source volume bar
   * Added volume matching between AmpliPi and Spotify and vice-versa
 
 # 0.4.11