Fix missing bold font

[neillrobson]

While using the production site, I noticed that much of the text was blurry/antialiased. Upon inspection, I saw that <strong> tags were in use, but the bold font weight was not being served for IBM Plex, leading to the blurry rendering.

This PR adds that font into the build, and also removes the stylelint-config-pretter dependency (due to deprecation and an installation conflict when I was attempting to set up the repository).

[vercel[bot]]

@neillrobson is attempting to deploy a commit to the Albric Trancart's projects Team on Vercel.

A member of the Team first needs to authorize it.

[neillrobson]

Closing due to lack of response/activity.