updating system dependency installs for GA actions

Author: finlaycampbell

.github/workflows/pkgdown.yaml

@@ -20,7 +20,7 @@ jobs:
 
       - name: Install system dependencies
         run: |
-          sudo apt-get install libcurl4-openssl-dev libharfbuzz-dev libfribidi-dev
+          sudo apt-get install libcurl4-openssl-dev libharfbuzz-dev libfribidi-dev libfontconfig1-dev libmagick++-dev
 
       - name: Query dependencies
         run: |