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

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] <support@github.com>

Author: dependabot[bot]

.github/workflows/build-dev-docs.yml

@@ -54,7 +54,7 @@ jobs:
     - name: Create archive
       run: git archive -o site.zip gh-pages
 
-    - uses: actions/upload-artifact@v5
+    - uses: actions/upload-artifact@v6
       with:
         name: docs
         path: site.zip

.github/workflows/build-rel-docs.yml

@@ -54,7 +54,7 @@ jobs:
     - name: Create archive
       run: git archive -o site.zip gh-pages
 
-    - uses: actions/upload-artifact@v5
+    - uses: actions/upload-artifact@v6
       with:
         name: docs
         path: site.zip

.github/workflows/publish-pkg.yml

@@ -72,7 +72,7 @@ jobs:
             echo "✅ Version matches tag"
           fi
 
-      - uses: actions/upload-artifact@v5
+      - uses: actions/upload-artifact@v6
         with:
           name: artifacts
           path: dist/*