ci: requires apt update

Author: paulmueller

.github/workflows/check.yml

@@ -29,6 +29,7 @@ jobs:
     - name: Setup xvfb (Linux)
       if: runner.os == 'Linux'
       run: |
+        sudo apt update
         sudo apt-get install -y xvfb libxkbcommon-x11-0 libxcb-icccm4 libxcb-image0 libxcb-keysyms1 libxcb-randr0 libxcb-render-util0 libxcb-shape0 libxcb-xinerama0 libxcb-xinput0 libxcb-xfixes0 libglib2.0-0 libgl1-mesa-dev
         sudo apt-get install '^libxcb.*-dev' libx11-xcb-dev libglu1-mesa-dev libxrender-dev libxi-dev libxkbcommon-dev libxkbcommon-x11-dev
         # start xvfb in the background