fix doc build

Author: echarlaix

.github/workflows/build_pr_documentation.yml

@@ -30,6 +30,8 @@ jobs:
 
       - name: Setup environment
         run: |
+          python -m venv venv-doc
+          source venv-doc/bin/activate
           pip uninstall -y doc-builder
           cd doc-builder
           git pull origin main