Don't run the tox matrix

Author: martinthomson

.github/workflows/python.yml

@@ -31,10 +31,10 @@ jobs:
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip
-        pip install tox black
+        pip install black -r python/requirements.txt
     - name: Reformat
       run: |
         cd python; black --check .
-    - name: Test with tox
+    - name: Run tests
       run: |
-        cd python; tox
+        cd python; nosetests