cli: fix release-pypi

[diegodelemos]

• The subprocess call to twine does not ask for user and password
  which makes the command fail. Using TWINE config environment
  variables the execution can be done totally unattended.

[tiborsimko]

The subprocess call to twine does not ask for user and password
which makes the command fail.

I was using ~/.pypirc, so the twine command was working fine unattended. Perhaps switch to using that as well?

Otherwise, if you want to add support for TWINE_* environment variables, please make it optional so that the above technique would still work.

[diegodelemos]

I opted to not consider ~/.pypirc as it contains the password in plain text (and the documentation page shows a warning about it). I think keeping support for TWINE_* env variables makes sense as I don't feel comfortable with having that plain text password for the REANA organisation on PyPI on my laptop. Said that, I will make the environment variables optional.

Edited:
Actually... I am closing the PR as no action needs to be taken for this env vars to work.

[tiborsimko]

I opted to not consider ~/.pypirc as it contains the password in plain text

(1) It does not need to contain password if you use keyring. Here is my setup:

$ cat ~/.pypirc
[distutils]
index-servers=
    pypi
    test

[pypi]
username = johndoe

and:

$ keyring set https://upload.pypi.org/legacy/ johndoe

In this way, there is no plain text password.

(2) Your laptop hard disk is probably having full-encryption in addition as well, isn't it?

[diegodelemos]

(1) I didn't follow the keyring path because I thought it would be a macos only solution, nice to know, thanks for sharing.

(2) Of course :)