[update] what's new for v5.2.6

Author: mafanya23

docs/whats_new.md

@@ -10,15 +10,14 @@ If you are updating Spreadsheet from an older version, check [Migration to Newer
 
 ## Version 5.2.6
 
-Released on November 18, 2025
+Released on November 19, 2025
 
 ### Fixes
 
 - An extra DOM element appearing during the import of an .xlsx file that contains a cell with a wrapped text
 - Incorrect displaying of column/row labels in the column context menu while managing columns
 - The sheet structure breaking when freezing a range that contains merged cells
 - Improved keyboard navigation in sheets with spanned cells
-- Export to Excel fails when a sheet contains a cell with a data-validation list
 
 ## Version 5.2.5