Update integration_tests.yml

.github/workflows/integration_tests.yml

@@ -15,7 +15,7 @@ jobs:
       - name: Set up Python ${{ env.PYTHON_VERSION }}
         uses: actions/setup-python@v1
         with:
-          python-version: ${{ matrix.python-version }}
+          python-version: ${{ env.PYTHON_VERSION }}
       - name: Install dependencies
         run: |
           python -m pip install --upgrade pip