activated canonical genre usage

.config/beets/config.yaml

@@ -72,6 +72,7 @@ lastgenre:
   prefer_specifig: yes  # prefer genre down the tree rather than the popular (often more generic)
   source: track         # artist/album/track for genre fetching
   whitelist: ~/.config/beets/whitelist.yaml
+  canonical: yes
 #  canonical: /path/to/genres-tree.yaml
 
 # run 'beet web', then access it on localhost:8337