INstall osmesa

Author: jorgensd

.github/actions/install-dependencies/action.yml

@@ -6,4 +6,4 @@ runs:
     - name: Install apt dependencies and upgrade pip
       shell: bash -el {0}
       run: |
-        apt-get update && apt-get install -y libxrender1
+        apt-get update && apt-get install -y libxrender1 libgl1-mesa-dev mesa-utils

.github/workflows/book_stable.yml

@@ -19,8 +19,8 @@ jobs:
     container: ghcr.io/fenics/dolfinx/lab:stable
 
     env:
-      PYVISTA_OFF_SCREEN: false
-      PYVISTA_JUPYTER_BACKEND: "html"
+      PYVISTA_OFF_SCREEN: true
+      PYVISTA_JUPYTER_BACKEND: html
 
     steps:
       - uses: actions/checkout@v5

.github/workflows/test_stable.yml

@@ -8,7 +8,6 @@ on:
 env:
   HDF5_MPI: "ON"
   HDF5_DIR: "/usr/local/"
-  DISPLAY: ":99.0"
   DEB_PYTHON_INSTALL_LAYOUT: deb_system
   LIBGL_ALWAYS_SOFTWARE: 1
 
@@ -18,6 +17,7 @@ jobs:
     container: ghcr.io/fenics/dolfinx/lab:stable
     env:
       PYVISTA_OFF_SCREEN: true
+      PYVISTA_JUPYTER_BACKEND: html
 
     # Steps represent a sequence of tasks that will be executed as part of the job
     steps: