CI: use builtin cache in actions/setup-python

.github/workflows/test.yml

@@ -18,15 +18,6 @@ jobs:
           - os: windows-latest
             python-version: pypy-3.9
         include:
-          - os: ubuntu-latest
-            pip-cache: ~/.cache/pip
-            poetry-cache: ~/.cache/pypoetry
-          - os: macos-latest
-            pip-cache: ~/Library/Caches/pip
-            poetry-cache: ~/Library/Caches/pypoetry
-          - os: windows-latest
-            pip-cache: ~\AppData\Local\pip\Cache
-            poetry-cache: ~\AppData\Local\pypoetry\Cache
           - os: ubuntu-latest
             python-version: 3.8
             build-docs: true
@@ -35,24 +26,19 @@ jobs:
             build-docs: true
     steps:
     - uses: actions/checkout@v4
+
+    - name: Install poetry
+      run: pipx install poetry
+
     - name: Set up Python ${{ matrix.python-version }}
       uses: actions/setup-python@v5
       with:
         python-version: ${{ matrix.python-version }}
+        cache: 'poetry'
         allow-prereleases: true
 
-    - uses: actions/cache@v4
-      with:
-        path: |
-          ${{ matrix.pip-cache }}
-          ${{ matrix.poetry-cache }}
-        key: ${{ runner.os }}-${{ hashFiles('**/pyproject.toml') }}
-        restore-keys: |
-          ${{ runner.os }}-
-
     - name: Install dependencies
       run: |
-        python -m pip install --upgrade poetry
         poetry install
     - name: Run tests
       run: |