Revert "test without caching"

This reverts commit a98ee70.

Author: twoertwein

.github/workflows/test.yml

@@ -28,6 +28,12 @@ jobs:
       run: echo "::set-output name=VERSION::$(poetry --version)"
       id: poetry_version
 
+    - name: Cache poetry.lock
+      uses: actions/cache@v3
+      with:
+        path: poetry.lock
+        key: ${{ matrix.os }}-${{ matrix.python-version }}-poetry-${{ steps.poetry_version.outputs.VERSION }}-${{ hashFiles('pyproject.toml') }}
+
     - name: Install project dependencies
       run: poetry install -vvv --no-root