fix: Add SkiaSharp dependencies for Ubuntu CI

- Install required system libraries for SkiaSharp on Ubuntu
- Add libfontconfig1, libfreetype6, libx11-6, libxext6, libxrender1, libxtst6
- Fix DllNotFoundException for libSkiaSharp in CI environment
- Ensure tests can run properly with SkiaSharp graphics library

Author: afonsoft

.github/workflows/ci-build-test.yml

@@ -31,6 +31,11 @@ jobs:
         with:
           dotnet-version: ${{ env.DOTNET_VERSION }}
 
+      - name: Install SkiaSharp Dependencies
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y libfontconfig1 libfreetype6 libx11-6 libxext6 libxrender1 libxtst6
+
       - name: Cache NuGet Packages
         uses: actions/cache@v5
         with: