fix path and streamline pip installs

.github/workflows/tests.yml

@@ -15,14 +15,14 @@ jobs:
         with:
           python-version: "3.9"
 
-      - name: Install pytest
-        run: |
-          pip install --upgrade pytest
-
       - name: Install dependencies
         run: |
           pip install -r requirements-tests.txt
 
+      - name: set pythonpath
+        run: |
+          echo "PYTHONPATH=src/axolotl" >> $GITHUB_ENV
+
       - name: Run tests
         run: |
           pytest tests/