Revert "use ubuntu"

This reverts commit 68eb262.

Author: dipinknair

.github/workflows/ci_cd.yml

@@ -47,7 +47,7 @@ jobs:
     runs-on: public-ubuntu-latest-8-cores
     timeout-minutes: 60
     container:
-      image: ubuntu:22.04
+      image: ghcr.io/ansys/mechanical:25.2.0
       options: --entrypoint /bin/bash
     needs: [style, doc-style]