Add isort and contest.py to CI style check

.github/workflows/test.yml

@@ -48,10 +48,11 @@ jobs:
       - name: Install dependencies
         run: |
           python -m pip install -U pip
-          python -m pip install -U black flake8
+          python -m pip install -U black flake8 isort
       - name: Check the style
         run: |
-          black -t py36 --check theano/ tests/ setup.py
+          black -t py36 --check theano/ tests/ setup.py conftest.py
+          isort --check theano/ tests/ setup.py conftest.py
           flake8
 
   test: