Fix button action handling to consistently use the active player

include/modules/mpris/mpris.hpp

@@ -78,6 +78,7 @@ class Mpris : public ALabel {
 
   PlayerctlPlayerManager* manager;
   PlayerctlPlayer* player;
+  PlayerctlPlayer* last_active_player_ = nullptr;
   std::string lastStatus;
   std::string lastPlayer;