ci: switch to newer versions of external github workflows

.github/workflows/build.yml

@@ -10,16 +10,15 @@ jobs:
         python-version: [ '3.8', '3.12' ]
     name: run tests on Python v${{ matrix.python-version }}
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
       - name: Setup Python
-        uses: actions/setup-python@v2
+        uses: actions/setup-python@v4
         with:
           python-version: ${{ matrix.python-version }}
       - name: Setup Poetry
-        uses: abatilo/actions-poetry@v2.1.3
+        uses: abatilo/actions-poetry@v2
       - name: Install Python packages
         run: |
-          poetry config experimental.new-installer false
           poetry install --no-root
       - name: Run tests
         run: |