Install missing package

Author: rs22

.github/workflows/gh-pages.yml

@@ -45,6 +45,9 @@ jobs:
       - name: Setup Graphviz
         uses: ts-graphviz/setup-graphviz@v2
 
+      - name: Setup rsvg-convert
+        run: sudo apt-get install -y librsvg2-bin
+
       - name: Railroad Diagrams
         run: |
           cd language/rrd