Update zpy description to reflect new backend (uv)

[AndydeCleyre]

Description

When zpy was added to this list, pip-tools was the sole backend. These days there's an additional, preferred backend: uv.

This change includes the new uv backend in zpy's description, instead of only the non-preferred pip-tools backend.

Type of changes

• A link to an external resource like a blog post -- link to uv
• Add/remove/update a link to a framework
• Add/remove/update a link to a plugin -- not the link, but the description
• Add/remove/update a link to a tab completion
• Add/remove/update a link to a theme
• Add/remove/update a link to a utility
• Text cleanups/typo fixes -- lowercase "environments"

Copyright Assignment

• This document is covered by the BSD License, and I agree to contribute this PR under the terms of the license. This is for the list submission, not for the project(s) you're adding, I don't care what license the plugins have as long as they have something.

Checklist

• I have read the CONTRIBUTING document.
• All new and existing tests passed.
• I have confirmed that the link(s) in my PR is valid.
• I have signed off my commits. You can use git commit --amend --no-edit --signoff to amend an existing commit, and you can find more details about signing off commits on the DCO GitHub action page here.
• My entries are single lines and are in the appropriate (plugins, themes, or completions) section, and in alphabetical order in their section.
• The completion/plugin/theme has a plugin file in the repository that conforms to the ZSH Plugin Standard - TLDR, there's a plugin file with a .plugin.zsh, .zsh or .sh suffix, it is not just bare instructions to be added to .zshrc
• Any added completions have a readme and a license file in their repository.
• Any added frameworks have a readme and a license file in their repository.
• Any added plugins have a readme and a license file in their repository.
• Any added themes have a screenshot, a readme, and a license file in their repository.
• Any added utilities have a readme and a license file in their repository.
• I have stripped any leading and/or trailing zsh-, zsh-plugin and/or oh-my-zsh- substrings from the link's displayed name. This makes it easier to find plugins/themes/completions by name by preventing big clusters in the O and Z sections of the list.

[unixorn]

lgtm.

Thanks, I appreciate the help keeping the list up to date.