fix(deps): drop `always-copy` virtualenv option

What does this merge request do and why?

This option was added in !713 (comment 1852491389) to ensure the Python interpreter exists even if Homebrew or asdf removes the file. However, this option doesn't necessarily help because it doesn't copy the Python shared library over. If a user uninstalls the needed Python version then the virtualenv will be broken in any case. In addition, mise doesn't work with this option since the shared library is a relative path. See https://github.com/mise-plugins/mise-poetry/issues/16 for more details.

In addition, Homebrew's virtualenv doesn't ship with the always-copy option: https://github.com/python-poetry/poetry/issues/9671

How to set up and validate locally

1. Wipe .venv via rm -rf .venv
2. Run poetry env use 3.11.10.
3. This should work fine in mise and asdf.

Merge request checklist

• Tests added for new functionality. If not, please raise an issue to follow up.
• Documentation added/updated, if needed.