[ci] is xquartz missing on macos?

.github/workflows/main.yml

           # set compiler flags
           mkdir -p ~/.R && echo -e 'CC=ccache clang\nCPP=ccache clang\nCXX=ccache clang++\nCXX11=ccache clang++\nCXX14=ccache clang++\nCXX17=ccache clang++\nCFLAGS=-isysroot /Library/Developer/CommandLineTools/SDKs/MacOSX10.13.sdk\nCCFLAGS=-isysroot /Library/Developer/CommandLineTools/SDKs/MacOSX10.13.sdk\nCXXFLAGS=-isysroot /Library/Developer/CommandLineTools/SDKs/MacOSX10.13.sdk\nCPPFLAGS=-isysroot /Library/Developer/CommandLineTools/SDKs/MacOSX10.13.sdk\nF77=ccache /usr/local/gfortran/bin/gfortran\nFC=ccache /usr/local/gfortran/bin/gfortran' > $HOME/.R/Makevars
 
-      # install freetype for {sysfonts}
-      - name: "[macOS] libfreetype"
+      # install xquartz for {sysfonts}
+      - name: "[macOS] xquartz"
         if: runner.os == 'macOS'
         run: |
-          brew install freetype
+          brew cask install xquartz
 
       # for some strange Windows reason this step and the next one need to be decoupled
       - name: "[Stage] Prepare"