[ruff]: Build loongarch64 binaries in CI (#20361)
<!--
Thank you for contributing to Ruff/ty! To help us out with reviewing,
please consider the following:
- Does this pull request include a summary of the change? (See below.)
- Does this pull request include a descriptive title? (Please prefix
with `[ty]` for ty pull
requests.)
- Does this pull request include references to any relevant issues?
-->
## Summary
<!-- What's the purpose of the change? What does it do, and why? -->
This PR adds support for building loongarch64 binaries in CI. As such
support has been merged in uv (astral-sh/uv#15387) it's time to consider
adding it to ruff.
Please note that as Ubuntu is not yet available for loongarch64, I have
elected to use a Debian Trixie container maintained by community
members. In addition, as Debian's pip does not allow installing modules
system-wide, I have modified the workflow to install additional modules
in a virtual environment.
Since the workflow is shared between all targets, the only way to handle
this difference (between Debian and Ubuntu) is just to install pip in a
venv for all targets. If there is a better (and less intrusive) way to
work around this, please let me know.
## Test Plan
Tests are included in CI and the loongarch64 artifacts built in [this
workflow](https://github.com/SkyBird233/ruff/actions/runs/17640270032/job/50125471548)
has been smoke tested.
