Export StringKey from DataTable module (#4760)

* Export StringKey from DataTable module

* Update CHANGELOG

Author: darrenburns

CHANGELOG.md

@@ -18,6 +18,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 - Raise `ValueError` with improved error message when number of cells inserted using `DataTable.add_row` doesn't match the number of columns in the table https://github.com/Textualize/textual/pull/4742
 - Add `Tree.move_cursor` to programmatically move the cursor without selecting the node https://github.com/Textualize/textual/pull/4753
 - Added `Footer` component style handling of padding for the key/description https://github.com/Textualize/textual/pull/4651
+- `StringKey` is now exported from `data_table` https://github.com/Textualize/textual/pull/4760
 
 ### Fixed
 

src/textual/widgets/data_table.py

@@ -10,6 +10,7 @@
     Row,
     RowDoesNotExist,
     RowKey,
+    StringKey,
 )
 
 __all__ = [
@@ -24,4 +25,5 @@
     "Row",
     "RowDoesNotExist",
     "RowKey",
+    "StringKey",
 ]