I propose to allow the `-` char in allowed label characters The reason is to allow to use more easily base64 ids, (like https://github.com/dylang/shortid, ...), uuid's too in labels
`-` is also not used as a query operator as a plus source: https://doxygen.postgresql.org/ltree_8h.html#a1cb5d5dd0c364d720854e8a250967dd1
