Fix #123107: Memory leak when deleting edit bones

The list of bone collections of an edit bone wasn't freed when deleting
that edit bone.

Thanks @lichtwerk for the fix!

source/blender/editors/armature/armature_utils.cc

@@ -129,6 +129,7 @@ void bone_free(bArmature *arm, EditBone *bone)
     }
   }
 
+  BLI_freelistN(&bone->bone_collections);
   BLI_freelinkN(arm->edbo, bone);
 }