Since page title and site title are the same on the homepage, this
would lead to having "Gajim - Gajim" for the homepage title. Setting
a different title if we are on the homepage fixes this.

https://github.com/halogenica/beautifulhugo/tree/master/i18n

It seems this version of BeautifulHugo theme has stronger integration
with katex. Simply removing katex from head.html/footer.html does
not work and leads to other errors.

This way updates to upstream can be applied easier later

Install: Add sudo to more install commands

See merge request gajim/website!15

Theme: Update highlight to latest upstream version

See merge request gajim/website!14

Fix deprecation warning

See merge request gajim/website!13