Add libgl flag to ci (jorgensd#238)

Author: jorgensd

.github/workflows/book_stable.yml

@@ -12,6 +12,7 @@ env:
   HDF5_DIR: "/usr/local/"
   DISPLAY: ":99.0"
   DEB_PYTHON_INSTALL_LAYOUT: deb_system
+  LIBGL_ALWAYS_SOFTWARE: 1
 
 jobs:
   build-book:
@@ -37,7 +38,7 @@ jobs:
         run: jupyter-book build . -W
 
       - uses: actions/upload-artifact@v4
-        if : always()
+        if: always()
         with:
           name: webpage
           path: ./_build/html

.github/workflows/test_nightly.yml

@@ -24,6 +24,7 @@ jobs:
       PYVISTA_OFF_SCREEN: true
       DISPLAY: ":99.0"
       PYVISTA_JUPYTER_BACKEND: html
+      LIBGL_ALWAYS_SOFTWARE: 1
 
     steps:
       - uses: actions/checkout@v4

.github/workflows/test_stable.yml

@@ -10,6 +10,7 @@ env:
   HDF5_DIR: "/usr/local/"
   DISPLAY: ":99.0"
   DEB_PYTHON_INSTALL_LAYOUT: deb_system
+  LIBGL_ALWAYS_SOFTWARE: 1
 
 jobs:
   test:
@@ -39,26 +40,26 @@ jobs:
           export LD_LIBRARY_PATH=/usr/local/dolfinx-complex/lib:$LD_LIBRARY_PATH
           python3 complex_mode.py
           mpirun -n 2 python3 complex_mode.py
-  
+
       - name: Test chapter 1
         working-directory: chapter1
         run: |
-            python3 -c "from pyvista import start_xvfb; start_xvfb(0.1)"
-            mpirun -n 2 python3 fundamentals_code.py
-            mpirun -n 2 python3 nitsche.py
-            mpirun -n 2 python3 membrane_code.py
+          python3 -c "from pyvista import start_xvfb; start_xvfb(0.1)"
+          mpirun -n 2 python3 fundamentals_code.py
+          mpirun -n 2 python3 nitsche.py
+          mpirun -n 2 python3 membrane_code.py
 
       - name: Test chapter 2
         working-directory: chapter2
-        run: |    
+        run: |
           mpirun -n 2 python3 diffusion_code.py
           mpirun -n 2 python3 heat_code.py
           mpirun -n 2 python3 linearelasticity_code.py
           mpirun -n 2 python3 hyperelasticity.py
           mpirun -n 2 python3 nonlinpoisson_code.py
           mpirun -n 2 python3 ns_code1.py
           mpirun -n 2 python3 ns_code2.py
-        
+
       - name: Test chapter 3
         working-directory: chapter3
         run: |
@@ -68,7 +69,7 @@ jobs:
           mpirun -n 2 python3 robin_neumann_dirichlet.py
           mpirun -n 2 python3 component_bc.py
           mpirun -n 2 python3 em.py
-  
+
       - name: Test chapter 4
         working-directory: chapter4
         run: |