fix convert db bug

Author: chenby

src/main/java/com/moilioncircle/redis/rdb/cli/ext/rdt/BackupRdbVisitor.java

@@ -22,8 +22,6 @@
 import java.io.OutputStream;
 import java.util.function.Supplier;
 
-import org.jetbrains.annotations.NotNull;
-
 import com.moilioncircle.redis.rdb.cli.cmd.Args;
 import com.moilioncircle.redis.rdb.cli.conf.Configure;
 import com.moilioncircle.redis.rdb.cli.glossary.Guard;