multimedia/qmmp-qt6: update to 2.1.4 release (+)

Qmmp 2.1.4 have been released

Changes since 2.1.3:

added projectM 4.0 support (experimental);
rebuild skin cache if missing (2.1.4 only);
fixed command execution under Windows in the file operations plugin;
fixed removing of the current playing file in the file operations plugin;
fixed crash on streams in the lyrics plugin;
fixed issues with tabbar in the simple ui plugin (2.1.4 only);
fixed issues with visualization windows on application startup.