add libfontconfig1-dev to CI for gpui linux font backend

Author: wilfreddenton

.github/workflows/ci.yml

@@ -25,7 +25,7 @@ jobs:
       - name: Install system dependencies
         run: |
           sudo apt-get update
-          sudo apt-get install -y libasound2-dev libxkbcommon-dev libwayland-dev libxcb1-dev libxkbcommon-x11-dev
+          sudo apt-get install -y libasound2-dev libxkbcommon-dev libwayland-dev libxcb1-dev libxkbcommon-x11-dev libfontconfig1-dev
 
       - name: Check formatting
         run: cargo fmt --all -- --check