Update sphinx.yml

Author: pancetta

.github/workflows/sphinx.yml

@@ -40,6 +40,7 @@ jobs:
       - name: Run nosetest
         run: |
           export PATH=/usr/share/miniconda/envs/test/bin/:$PATH
+          which python
           which mpirun
           nosetests -v --with-timer --with-coverage --cover-erase --cover-inclusive --cover-package=pySDC/core,pySDC/implementations,pySDC/helpers,pySDC/tutorial,pySDC/projects --cover-html --cover-html-dir=doc/build/test_coverage pySDC/tests