CI: Use Poetry for dependency installation

.github/workflows/ci.yml

@@ -20,11 +20,9 @@ jobs:
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip
-        pip install ruff mypy pytest pytest-cov
-        if [ -f requirements.txt ]; then pip install -r requirements.txt; fi
-        # If using poetry:
-        # pip install poetry
-        # poetry install
+        pip install poetry
+        poetry config virtualenvs.create false
+        poetry install --no-interaction --no-ansi
         
     - name: Lint with Ruff
       run: |