uses python 3.9 for integration tests

Author: lresende

.github/workflows/build.yml

@@ -33,7 +33,6 @@ jobs:
       - name: Install Python dependencies
         run: |
           pip install ".[test]"
-          pip install --upgrade cloudpickle
       - name: Build and install Jupyter Enterprise Gateway
         uses: nick-invision/retry@v3.0.0
         with:
@@ -59,6 +58,8 @@ jobs:
           export SPARK_VERSION=3.2.1
           # Run integration tests with debug output
           make itest-yarn-debug
+        with:
+          python-version: "3.9"
       - name: Collect logs
         if: success() || failure()
         run: |