Further build isolation

Author: jorgensd

.github/workflows/test_stable.yml

@@ -29,7 +29,7 @@ jobs:
       - name: Install additional deps
         run: |
           python3 -m pip install -U pip setuptools pkgconfig poetry-core
-          python3 -m pip install --no-binary=h5py .[netgen]
+          python3 -m pip install --no-binary=h5py --no-build-isolation .[netgen]
 
       - name: Test complex notebooks in parallel
         working-directory: chapter1