rm HashCode, use DenominationHash directly

src/pg_type.ml

@@ -4,6 +4,9 @@ open Bin_type
 open Api
 open Caqti_type
 
+(* TODO
+   check that we use Caqti_type.octets for binary data *)
+
 let amount : Amount.t t =
   let open Amount in
   custom
@@ -25,7 +28,7 @@ let eddsa_sig = EddsaSignature.caqti
 (* todo: enum type for wire_method? *)
 let wire_method = Caqti_type.string
 let payto_uri = Caqti_type.string
-let b32 = Api.B32.caqti
+let b32 = B32.caqti
 
 include struct
   (* alias for hash *)