Worker update and more

Fixes and updates. Also a few breaking changes, see below for details...

[0.31.0] - 2023-08-01

Added

• Added App.begin_capture_print, App.end_capture_print, Widget.begin_capture_print, Widget.end_capture_print #2952
• Added the ability to run async methods as thread workers #2938
• Added App.stop_animation #2786
• Added Widget.stop_animation #2786

Changed

• Breaking change: Creating a thread worker now requires that a thread=True keyword argument is passed #2938
• Breaking change: Markdown.load no longer captures all errors and returns a bool, errors now propagate #2956
• Breaking change: the default style of a DataTable now has max-height: 100% #2959

Fixed

• Fixed a crash when a SelectionList had a prompt wider than itself #2900
• Fixed a bug where Click events were bubbling up from Switch widgets #2366
• Fixed a crash when using empty CSS variables #1849
• Fixed issue with tabs in TextLog #3007
• Fixed a bug with DataTable hover highlighting #2909