Update tests.yaml

Don't run reorder-python-imports as there is a conflict with black, see psf/black#4175

.github/workflows/tests.yaml

@@ -34,7 +34,7 @@ jobs:
 
       - name: Install Python modules
         run: |
-          pip install --constraint=.github/workflows/constraints.txt pre-commit black flake8 reorder-python-imports
+          pip install --constraint=.github/workflows/constraints.txt pre-commit black flake8
 
       - name: Run pre-commit on all files
         run: |