assets/webapp.css: Disable common ligatures of Alegreya font
assets/webapp.css: Disable common ligatures of Alegreya font

The Alegreya font we are using ships some ligatures producing confusing
text rendering, for instance the ligatures for `~` and some characters.

So disable font common ligatures with CSS.

SoftwareHeritage/swh-web-ui,SoftwareHeritage/swh-web-ui,SoftwareHeritage/swh-web-ui