tests: fix changed module name

.github/workflows/unit-tests.yml

@@ -22,7 +22,7 @@ jobs:
 
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v6
+        uses: actions/checkout@v4
 
       - name: Set up Python
         uses: actions/setup-python@v5
@@ -38,8 +38,6 @@ jobs:
           python -m pip install -e ".[test]"
 
       - name: Run tests
-        env:
-          PYTHONPATH: ${{ github.workspace }}
         run: |
           set -euo pipefail
           pytest -q