Missing font code-fork after upgrading from v0.4 to v0.5

[sschnabe]

After upgrading to v0.5.0 simple project fails:

mdbook build:
Book building has started
Running the html backend
ERROR Rendering failed
 	Caused by: Error rendering "index" line 177, col 29: Missing font code-fork
 	Caused by: Missing font code-fork

Do you have a clue why?

[book]
authors = ["Stephan Schnabel"]
language = "en"
text-direction = "ltr"
src = "src"
title = "kokuwa.io"

[output.html]
additional-css = ["src/custom.css"]
git-repository-url = "https://git..."
git-repository-icon = "fa-code-fork"
edit-url-template = "https://git.../_edit/main/{path}"