multimedia/qmmp-qt6: update to 2.3.1 release (+):

Changes since 2.3.0:
added IMA ADPCM support;
fixed grouping by parent directory;
fixed sorting by file name and path;
fixed detection of the PCM WAVE files with "JUNK", "bext" and "fact" chunks;
fixed color scheme change issues;
fixed drawing issues in the plugin list;
updated Chinese Simplified translation.