Update the if again

Following the example from here: https://docs.github.com/en/actions/using-workflows/workflow-syntax-for-github-actions#example-using-contexts

.github/workflows/CI.yml

@@ -21,7 +21,7 @@ jobs:
         pip install -U pip setuptools
         pip install -e.[globus,test]
     - name: Start Redis
-      if: runner.os == "Linux"
+      if: ${{ runner.os == 'Linux' }}
       uses: supercharge/redis-github-action@1.4.0
     - name: Lint with flake8
       run: |