Add reserved field

Author: gbrgr

proto/relationalai/lqp/v1/transactions.proto

@@ -126,6 +126,7 @@ message ExportIcebergConfig {
   IcebergLocator locator = 1;
   IcebergCatalogConfig config = 2;
   RelationId table_def = 3;              // Which definition to export as a table.
+  reserved 4;                            // was: repeated ExportColumn columns
   optional string prefix = 5;            // File name prefix for parquet files that are produced.
   optional int64 target_file_size_bytes = 6;
   string compression = 7;