fix(cat-voices): signed document signing (#2341)

Author: dt-iohk

catalyst_voices/packages/internal/catalyst_voices_repositories/lib/src/signed_document/signed_document_manager_impl.dart

@@ -89,7 +89,7 @@ final class _CatalystSigner implements CatalystCoseSigner {
   );
 
   @override
-  StringOrInt? get alg => const IntValue(CoseValues.eddsaAlg);
+  StringOrInt? get alg => null;
 
   @override
   Future<Uint8List?> get kid async {

catalyst_voices/packages/libs/catalyst_cose/lib/src/cose_sign.dart

@@ -179,13 +179,7 @@ final class CoseSign extends Equatable {
       payload: CborBytes(payload),
     );
 
-    return Uint8List.fromList(
-      cbor.encode(
-        CborBytes(
-          cbor.encode(sigStructure),
-        ),
-      ),
-    );
+    return Uint8List.fromList(cbor.encode(sigStructure));
   }
 
   static CborList _createCoseSignSigStructure({