Bump actions/upload-artifact from 4 to 6

Bumps [actions/upload-artifact](https://github.com/actions/upload-artifact) from 4 to 6.
- [Release notes](https://github.com/actions/upload-artifact/releases)
- [Commits](actions/upload-artifact@v4...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] <support@github.com>

Author: dependabot[bot]

.github/workflows/publish.yml

@@ -18,7 +18,7 @@ jobs:
     - uses: actions/checkout@v6
     - name: Build sdist
       run: pipx run build --sdist
-    - uses: actions/upload-artifact@v4
+    - uses: actions/upload-artifact@v6
       with:
         if-no-files-found: error
         compression-level: 0
@@ -38,7 +38,7 @@ jobs:
     - uses: actions/checkout@v6
     - name: Build wheels
       uses: pypa/cibuildwheel@v3.3.0
-    - uses: actions/upload-artifact@v4
+    - uses: actions/upload-artifact@v6
       with:
         if-no-files-found: error
         compression-level: 0