Merge pull request #2814 from SasView/fix_ubuntu_latest

As agreed at today's call we will merge this. Thanks for the note @klytje -- I think that was the consensus that if it could easily be re-implemented should it get accidentally overwritten.  So here goes the merge.

.github/workflows/ci.yml

@@ -81,6 +81,7 @@ jobs:
       - name: Install X11 libraries (Linux)
         if: ${{ startsWith(matrix.os, 'ubuntu') }}
         run: |
+          sudo apt-get update
           sudo apt install libxkbcommon-x11-0 libxcb-icccm4 libxcb-image0 libxcb-keysyms1 libxcb-randr0 libxcb-render-util0 libxcb-xinerama0 libxcb-xfixes0 x11-utils xvfb libegl-dev
 
       - name: Install Python dependencies
@@ -398,6 +399,7 @@ jobs:
       - name: Install X11 libraries (Linux)
         if: ${{ startsWith(matrix.os, 'ubuntu') }}
         run: |
+          sudo apt-get update
           sudo apt install libxkbcommon-x11-0 libxcb-icccm4 libxcb-image0 libxcb-keysyms1 libxcb-randr0 libxcb-render-util0 libxcb-xinerama0 libxcb-xfixes0 x11-utils xvfb
 
       - name: Try running the installation (Linux)