build(deps): bump actions/upload-artifact from 5 to 6 (libuv#4975)

Bumps [actions/upload-artifact](https://github.com/actions/upload-artifact) from 5 to 6.
- [Release notes](https://github.com/actions/upload-artifact/releases)
- [Commits](actions/upload-artifact@v5...v6)

---
updated-dependencies:
- dependency-name: actions/upload-artifact
  dependency-version: '6'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

.github/workflows/CI-win.yml

@@ -97,7 +97,7 @@ jobs:
              `${{ matrix.config.arch }}-w64-mingw32-gcc -print-file-name=libatomic-1.dll` \
              build/usr/bin
       - name: Upload build artifacts
-        uses: actions/upload-artifact@v5
+        uses: actions/upload-artifact@v6
         with:
           name: mingw-${{ matrix.config.arch }}
           path: build/usr/**/*