Try running test suite with single core

Author: ericpre

.github/workflows/tests.yml

@@ -112,7 +112,7 @@ jobs:
 
       - name: Run test suite
         run: |
-          pytest ${{ env.PYTEST_ARGS }} -n ${{ steps.cpus.outputs.count }} --cov=. --cov-report=xml -v
+          pytest ${{ env.PYTEST_ARGS }} -n 1 --cov=. --cov-report=xml -v
 
       - name: Run doctest (Docstring)
         if: ${{ matrix.OLDEST_SUPPORTED_VERSION == 'false'}}