Add fonts to support emoji and box-drawing characters in PDF

.github/workflows/epub.yml

@@ -45,7 +45,7 @@ jobs:
 
       - name: Install Pandoc and fonts
         run: |
-          sudo apt-get install -y pandoc fonts-noto-cjk fonts-noto-cjk-extra
+          sudo apt-get install -y pandoc fonts-noto-cjk fonts-noto-cjk-extra fonts-noto-color-emoji fonts-dejavu
 
       - name: Install mdbook-pandoc
         run: |

book.toml

@@ -31,7 +31,7 @@ output-file = "rust-course.pdf"
 pdf-engine = "tectonic"
 pdf-engine-opt = ["-Z", "continue-on-errors"]
 to = "pdf"
-variables = { mainfont = "Noto Sans CJK SC", sansfont = "Noto Sans CJK SC", CJKmainfont = "Noto Sans CJK SC" }
+variables = { mainfont = "Noto Sans CJK SC", sansfont = "Noto Sans CJK SC", CJKmainfont = "Noto Sans CJK SC", monofont = "DejaVu Sans Mono" }
 
 [output.pandoc.profile.epub]
 output-file = "rust-course.epub"