merge test_exercises.py and test_exercises_docker.py

docker-compose.yml

@@ -4,6 +4,6 @@ services:
   test-runner:
     image: exercism/python-test-runner
     working_dir: /python
-    entrypoint: ./bin/test_runner_exercises.py
+    entrypoint: ./bin/test_exercises.py --runner test-runner
     volumes:
       - .:/python