Log Message:
py-sigal: update to 2.4.

Version 2.4
~~~~~~~~~~~

Released on 2023-09-29.

Sigal now requires Pillow>=8.0.0

- Avoid IndexError with empty source dir [:issue:`498`].
- New cli option ``--force-album`` to reprocess only specific albums
  [:issue:`491`].
- Added support for black detection in video thumbnail generation
  [:issue:`485`].
- Don't show the galleria container if there are no medias [:issue:`484`].
- Force encrypt's password form to be on top [:issue:`483`].
- Add mkv to ``video_extensions`` [:issue:`481`].
- Make sure ``zip_gallery`` is set correctly [:issue:`477`].
- Updates for recent Pillow changes, requires Pillow>=8.0.0 [:issue:`479`].
- Make theme dir writable after copying to it [:issue:`471`].
- New plugin: Titleregexp - modify titles of albums with regular expressions
  [:issue:`469`].
- List of sort-properties as fallback instead of zero-length string
  [:issue:`468`].