Don't write output to stdout

[jenshnielsen]

Writing output to stdout breaks the usage of artifacts-keyring with the keyring CLI since it is impossible to discriminate between the output of the CLI and other text written to stdout.

See https://github.com/astral-sh/uv/issues/3260 as an example where this is an issue but note that this also affects using a system wide install of keyring as a backend with pip.

[embetten]

This looks reasonable to me - thank you for your contributions. We will do some validations before merging

[PanTheDev]

Will this be merged and released soon? It's a pain to retry auth because it randomly fails because of this issue.

[jenshnielsen]

@embetten Any chance this could be merged and released soon? It would make our work flow so much easier with azure artifacts