test pypi setup

.circleci/config.yml

           command: |
             . venv/bin/activate
             cd << parameters.directory >>
-            twine upload -u mlagents -p $PYPI_PASSWORD dist/*
+            twine upload -u mlagents-test -p $PYPI_PASSWORD --repository-url https://test.pypi.org/legacy/ dist/*
 
 workflows:
   version: 2

gym-unity/gym_unity/__init__.py

-__version__ = "0.12.1"
+__version__ = "0.12.1.dev0"

ml-agents-envs/mlagents_envs/__init__.py

-__version__ = "0.12.1"
+__version__ = "0.12.1.dev0"

ml-agents/mlagents/trainers/__init__.py

-__version__ = "0.12.1"
+__version__ = "0.12.1.dev0"