Fix workdir in DOckerfile

Author: PavelCz

Dockerfile

@@ -45,7 +45,7 @@ COPY . /reward_preprocessing
 RUN python setup.py sdist bdist_wheel
 RUN pip install dist/reward_preprocessing-*.whl
 
-# Move into src directory, so scripts can be run from outside the docker container.
-CMD cd src/
+# Set to src directory so scripts can be run as python -m reward_preprocessing. ...
+WORKDIR /reward_preprocessing/src/
 
 CMD ["pytest"]