ci: simplify install command

.github/workflows/test-suite.yml

@@ -27,7 +27,7 @@ jobs:
       run: |
         python -m pip install --upgrade pip
         pip install numpy
-        if [ -f requirements.txt ]; then pip install -e ".[test]"; fi
+        pip install -e .
     - name: Test with pytest
       run: |
         python -m pytest -v -x automated_test.py