Bump ansys/actions from 5 to 6

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

---
updated-dependencies:
- dependency-name: ansys/actions
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

.github/workflows/ci_cd.yml

@@ -153,7 +153,7 @@ jobs:
           .ci/waiting_services.sh
 
       - name: "Run Ansys documentation building action"
-        uses: ansys/actions/doc-build@v5
+        uses: ansys/actions/doc-build@v6
         with:
           requires-xvfb: true
           python-version: ${{ env.MAIN_PYTHON_VERSION }}