CI: install required libraries on linux

.github/workflows/rust.yml

@@ -49,10 +49,10 @@ jobs:
           profile: minimal
           toolchain: stable
           override: true
+      - run: sudo apt-get install libxcb-render0-dev libxcb-shape0-dev libxcb-xfixes0-dev
       - uses: actions-rs/cargo@v1
         with:
           command: test
-          args: -p egui -p egui_demo_lib # TODO: fix weird build issues with the others
 
   fmt:
     name: Rustfmt