typo fix

Author: saska

src/textual/widgets/_data_table.py

@@ -1040,7 +1040,7 @@ def get_row_key(self, row_index: int) -> RowKey:
             row_index: The index of the row.
 
         Returns:
-            Thhe current key of the specified row index.
+            The current key of the specified row index.
 
         Raises:
             RowDoesNotExist: If there is no row with the given index.