fix: TS define update

Author: zombieJ

src/interface.ts

@@ -89,7 +89,7 @@ export interface ColumnType<RecordType> extends ColumnSharedType<RecordType> {
 
 export type ColumnsType<RecordType> = (ColumnGroupType<RecordType> | ColumnType<RecordType>)[];
 
-export type GetRowKey<RecordType> = (record: RecordType, index: number) => Key;
+export type GetRowKey<RecordType> = (record: RecordType, index?: number) => Key;
 
 // ================= Fix Column =================
 export interface StickyOffsets {