Try to fix action to use Mulish font

Author: jsteyn

.github/workflows/build.yml

@@ -6,9 +6,17 @@ jobs:
     steps:
       - name: Set up Git repository
         uses: actions/checkout@v4
+      - name: Install Mulish font
+        run: |
+          mkdir -p ~/.local/share/fonts
+          curl -L -o /tmp/mulish.zip https://github.com/google/fonts/raw/main/ofl/mulish/Mulish%5Bwght%5D.ttf
+          cp /tmp/mulish.zip ~/.local/share/fonts/Mulish.ttf
+          fc-cache -fv
       - name: Compile slide
         uses: xu-cheng/latex-action@v2
         with:
+          extra_fonts: |
+            ./path/to/custom.ttf
           root_file: slides.tex
           latexmk_use_lualatex: true
       - name: Upload slides PDF file