fix syntax of datomic attribute type.

clj/clarity/clarity/types.clj

    {:error (str "Expected value of type Map, but got value " val ".")}))
(def datomic-attr-type
  '(HMap :mandatory {:db/id (Value "#db/id[db.part/db]")
  '(HMap :mandatory {:db/id (Value "#db/id[:db.part/db]")
                     :db/ident Keyword
                     :db/valueType (U (Value :db.type/keyword)
                                      (Value :db.type/string)