Explicitly activate the environment (#2534)

Author: pamelafox

.github/workflows/python-test.yaml

@@ -36,6 +36,7 @@ jobs:
             version: "0.4.20"
             cache-dependency-glob: "requirements**.txt"
             python-version: ${{ matrix.python_version }}
+            activate-environment: true
         - name: Setup node
           uses: actions/setup-node@v4
           with: