CI: adapt to new isntallation method

.github/workflows/ci-build-tests.yml

@@ -13,7 +13,7 @@ jobs:
       run: |
         python -m pip install --upgrade pip
         pip install flake8 pytest
-        pip install -r requirements.txt
+        pip install .
     - name: Lint with flake8
       run: |
         # stop the build if there are Python syntax errors or undefined names
@@ -28,4 +28,5 @@ jobs:
         sudo -u postgres createuser -s runner
     - name: Test with pytest
       run: |
-        pytest tests/
+        python3 setup.py build
+        pytest tests