feat(ci): install poetry via pipx

Fixes the warning related to using the root environment's pip when install poetry via `pip install poetry`.

.github/workflows/test.yml

@@ -12,15 +12,16 @@ jobs:
       with:
         persist-credentials: false
 
+    - name: Install poetry
+      run: pipx install poetry
+
     - name: Set up Python
       uses: actions/setup-python@v5
       with:
         python-version: "3.11"
 
     - name: Install dependencies
-      run: |
+      run: poetry install --with dev
-        pip install poetry
-        poetry install --with dev 
 
     - name: Run tests
       run: poetry run pytest