Ensure actions/checkout is performed before astral-sh/setup-uv

I was looking into a failed stable doc deployment and noticed that the action `doc-deploy-stable` is installing `uv` before performing a checkout of the repo. This shows the following warning in the logs

and I think this highlights that if a user wants to reuse `uv` cache, it will not work as expected because `setup-uv` does not have access to the information necessary for its cache management.

A simple fix should be to reorder the steps of the action. Note that this might also concern other actions and anyone handling this issue should have a look in the whole repo if possible :)

Search the repository's GitHub Actions definitions for doc-deploy-stable and every use of astral-sh/setup-uv; start by checking the step order around setup-uv and actions/checkout. Done means checkout precedes setup-uv wherever this applies, including any other affected actions, so uv cache management has the required repository information.

Written by the indexing model from the issue text.