tests.yml: apt-get install install libgl1-mesa-glx

fixes "libGL.so.1: cannot open shared object file"

.github/workflows/tests.yml

@@ -21,6 +21,7 @@ jobs:
           pip3 install --upgrade pip
           pip3 install -e .
           pip3 install -e .[dev]
+          apt-get update && apt install -y libgl1-mesa-glx
       - name: Run tests
         run: |
           python3 -m pytest -v