chore(python_dorenv): revert python_dotenv to earlier
# test dependencies
pytest>=2.8.2
responses==0.9.0
-python_dotenv>=0.10.0;python_version < '3.7'
-python_dotenv==0.9.0;python_version >= '3.7'
+python_dotenv>=0.1.5;python_version!='3.2'
pylint>=1.4.4
tox>=2.9.1
pytest-rerunfailures>=3.1
