chore(deps): bump actions/upload-artifact from 4.3.4 to 4.3.6

Bumps [actions/upload-artifact](https://github.com/actions/upload-artifact) from 4.3.4 to 4.3.6.
- [Release notes](https://github.com/actions/upload-artifact/releases)
- [Commits](actions/upload-artifact@v4.3.4...v4.3.6)

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

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

.github/workflows/sphinxbuild.yml

@@ -23,7 +23,7 @@ jobs:
       shell: bash
       run: tar czf /tmp/documentation.tar.gz -C user_manual/_build/html .
     - name: Upload static documentation
-      uses: actions/[email protected].4
+      uses: actions/[email protected].6
       with:
         name: User manual.zip
         path: "/tmp/documentation.tar.gz"
@@ -55,7 +55,7 @@ jobs:
       shell: bash
       run: tar czf /tmp/documentation.tar.gz -C developer_manual/_build/html/com .
     - name: Upload static documentation
-      uses: actions/[email protected].4
+      uses: actions/[email protected].6
       with:
         name: Developer manual.zip
         path: "/tmp/documentation.tar.gz"
@@ -75,7 +75,7 @@ jobs:
       shell: bash
       run: tar czf /tmp/documentation.tar.gz -C admin_manual/_build/html/com .
     - name: Upload static documentation
-      uses: actions/[email protected].4
+      uses: actions/[email protected].6
       with:
         name: Administration manual.zip
         path: "/tmp/documentation.tar.gz"