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] <[email protected]>

Author: dependabot[bot]

.github/workflows/docs-build-pr.yaml

@@ -39,7 +39,7 @@ jobs:
           sudo mv _build/docs/review/latest/* _build/docs
           sudo rm -rf _build/docs/review _build/docs/tmp _build/docs/sphinx_warnings.txt
       - name: Upload HTML
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@v6
         with:
           name: html-build-artifact
           path: _build/docs
@@ -52,7 +52,7 @@ jobs:
           echo ${{ github.event.pull_request.merged }} > ./pr/merged.txt
           echo ${{ github.event.action }}              > ./pr/action.txt
       - name: Upload PR information
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@v6
         with:
           name: pr
           path: pr/

.github/workflows/docs-build.yaml

@@ -108,7 +108,7 @@ jobs:
           mv _build/docs/review/latest/* _build/docs
           rm -rf _build/docs/review _build/docs/tmp _build/docs/sphinx_warnings.txt
       - name: Upload HTML
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@v6
         with:
           name: html-build-artifact
           path: _build/docs
@@ -123,7 +123,7 @@ jobs:
           echo ${{ github.event.action }}              > ./pr/action.txt
       - name: Upload PR information
         if: ${{ github.event_name == 'pull_request' }}
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@v6
         with:
           name: pr
           path: pr/