Change sdist build command to use 'uv' (#641)

* Change sdist build command to use 'uv'

Since the guide was heavily using `uv` already, it's probably a good idea to also reference `uv build --sdist` as the primary option.

* style: pre-commit fixes

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

Author: tobiasdiez

docs/pages/guides/gha_wheels.md

@@ -83,18 +83,20 @@ make_sdist:
       with:
         fetch-depth: 0 # Optional, use if you use setuptools_scm
         submodules: true # Optional, use if you have submodules
+    - uses: astral-sh/setup-uv@v6
 
     - name: Build SDist
-      run: pipx run build --sdist
+      run: uv build --sdist
 
     - uses: actions/upload-artifact@v4
       with:
         name: cibw-sdist
         path: dist/*.tar.gz
 ```
 
-You can instead install build via pip and use `python -m build --sdist`. You can
-also pin the version with `pipx run build==<version>`.
+Instead of using `uv`, you can also run `pipx run build --sdist`, or install
+build via pip and use `python -m build --sdist`. You can also pin the version
+with `pipx run build==<version>`.
 
 ## The core job (3 main OS's)