Upgrade Jekyll to v4.4

[fzaninotto]

Currently, the version of Jekyll used to build gh-pages is v3.10.0 (dated June 24, 2024).

A more recent version of Jekyll, v4.4, offers a neat feature that many developers could benefit from: Marking specific lines in a code snippet.

https://jekyllrb.com/docs/liquid/tags/#marking-specific-lines

Would you be open to an update of the version of Jekyll used in the action? If not, what are the blockers?

Thanks in advance.