task(ci): add cache for virtual environment

.github/workflows/run-tests.yml

@@ -20,6 +20,17 @@ jobs:
           python-version: ${{ matrix.python-version }}
       - name: Install poetry
         uses: abatilo/actions-poetry@v3.0.0
+      # Cache the virtual environment to speed up build time
+      # See https://github.com/marketplace/actions/python-poetry-action#workflow-example-cache-the-virtual-environment
+      - name: Set up a local virtual environment
+        run: |
+          poetry config virtualenvs.create true --local
+          poetry config virtualenvs.in-project true --local
+      - uses: actions/cache@v3
+        name: Define cache for the virtual environment
+        with:
+          path: ./.venv
+          key: venv-${{ hashFiles('poetry.lock') }}
       - name: Install dependencies
         run: poetry install
       - name: Run tests