feat: display keyring stderr

[samypr100]

Summary

Closes #4162

Changes keyring subprocess to allow display of stderr.
This aligns with pip's behavior since pip 23.1.

Test Plan

• Tested using gnome-keyring-backend on a self-hosted private registry as well as the keyring script described in Keyring stderr is not displayed #4162 to confirm both existing functionality and the new stderr display.
• Existing tests using scripts/packages/keyring_test_plugin are now showing its stderr output as well.

[zanieb]

Thanks!