Adjust pythonpath in test workflow

Author: bjthres1

.github/workflows/python-package.yml

@@ -37,4 +37,5 @@ jobs:
         flake8 . --count --exit-zero --max-complexity=10 --max-line-length=127 --statistics
     - name: Test with pytest
       run: |
+        export PYTHONPATH=$PYTHONPATH:$(pwd)
         pytest