GA: remove use of kisak PPA

Author: pablode

.github/workflows/run-tests.yml

@@ -151,8 +151,6 @@ jobs:
 
     - name: Install packages
       run: |
-        # Use latest stable mesa because Storm requires OpenGL 4.6
-        sudo add-apt-repository ppa:kisak/kisak-mesa
         sudo apt update
         sudo apt upgrade
         sudo apt-get install mesa-utils xvfb qtbase5-dev