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## Summary
From my reading of the [UV
docs](https://docs.astral.sh/uv/guides/scripts/), `mirror.py` would be a
good example of a standalone script. This PR updates `mirror.py` and the
`main.yml` workflow to be a UV script and makes use of UV in the update
process.
## Test Plan
- Update the uv version (currently 0.8.4) to an older version e.g. 0.8.3
in both `pyproject.toml` and `README.md`
- Run `uv run --no-project mirror.py` to check the update process still
works as expected
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## Summary
`uv` is great. So we should use it where we can.
The cache had to be removed because the workflow breaks currently.
https://github.com/actions/setup-python/issues/822
When this is solved, caching can be brought back in.
## Test Plan
Ran workflow on my local repo.
