Always install and run mdbook-pandoc (#1713)

Before, we only installed and ran `mdbook-pandoc` when publishing the
course — which means that a PR change could accidentally break the
publish workflow. We now test that it works on every PR.

From a discussion in #1704.

.github/workflows/install-mdbook/action.yml

@@ -15,6 +15,14 @@ runs:
       run: cargo install mdbook-svgbob --locked --version 0.2.1
       shell: bash
 
+    - name: Install mdbook-pandoc and related dependencies
+      run: |
+        cargo install mdbook-pandoc --locked --version 0.5.0
+        sudo apt-get install -y texlive texlive-luatex texlive-lang-cjk librsvg2-bin fonts-noto
+        curl -LsSf https://github.com/jgm/pandoc/releases/download/3.1.11/pandoc-3.1.11-linux-amd64.tar.gz | tar zxf -
+        echo "$PWD/pandoc-3.1.11/bin" >> $GITHUB_PATH
+      shell: bash
+
     - name: Install mdbook-i18n-helpers
       run: cargo install mdbook-i18n-helpers --locked --version 0.3.1
       shell: bash