Fix snapshot sequence number

Author: SergeiPatiakin

iceberg-rust/src/table/transaction/operation.rs

@@ -208,11 +208,13 @@ impl Operation {
                     (_, _) => Ok(SnapshotOperation::Overwrite),
                 }?;
 
+                let snapshot_sequence_number = table_metadata.last_sequence_number
+                    + if dsn_offset >= 1 { dsn_offset } else { 1 };
                 let mut snapshot_builder = SnapshotBuilder::default();
                 snapshot_builder
                     .with_snapshot_id(snapshot_id)
                     .with_manifest_list(new_manifest_list_location)
-                    .with_sequence_number(table_metadata.last_sequence_number + 1)
+                    .with_sequence_number(snapshot_sequence_number)
                     .with_summary(Summary {
                         operation: snapshot_operation,
                         other: additional_summary.unwrap_or_default(),