[fix] remove ambiguous import

lib/modules/blockchain/blockchain/src/sync/download/json_reader_worker.rs

@@ -13,7 +13,6 @@
 // You should have received a copy of the GNU Affero General Public License
 // along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
-use crate::constants::*;
 use crate::sync::*;
 use dubp_documents::parsers::blocks::parse_json_block;
 use dubp_documents::Blockstamp;