bump crengine: fix CSS cascade, support :is(), other fixes (#1724)

Includes:
- Fix getToc() not cached on initial loading
- CSS: add support for forgotten "border-style: hidden"
- CSS: fix parsing of 'div :something' and 'div [attr]'
- CSS: fix checking E[foo~="value"]
- CSS: order rules as written when building a selector
- CSS: fix useragent vs. author stylesheet CSS cascade
- CSS: pass useragent_sheet flag all along parse() code
- CSS: add private selector syntax to match against text
- CSS: add support for :is(), :where() and :not() pseudoclasses
- EPUB: don't ignore any <spine> item
- bump CACHE_FILE_FORMAT_VERSION