Snap: fix enchant after core20 update

5402a6d broke enchant's loading of backends due to the
change to enchant 2 which uses a different location. Update
paths mapping in snapcraft.yaml accordingly.

snap/snapcraft.yaml

@@ -32,8 +32,8 @@ layout:
     symlink: $SNAP/usr/share/hunspell
   /usr/share/myspell:
     symlink: $SNAP/usr/share/myspell
-  /usr/lib/$SNAPCRAFT_ARCH_TRIPLET/enchant:
-    symlink: $SNAP/usr/lib/$SNAPCRAFT_ARCH_TRIPLET/enchant
+  /usr/lib/$SNAPCRAFT_ARCH_TRIPLET/enchant-2:
+    symlink: $SNAP/usr/lib/$SNAPCRAFT_ARCH_TRIPLET/enchant-2
 
 apps:
   poedit: