docs: Move publishing to stable release (#48)

Make sure docs gets published only on stable releases.
---

### **Checklist**
- [ ] Tests added/updated
- [ ] Documentation updated (if needed)
- [ ] Code conforms to style guidelines

---------

Signed-off-by: Roaa Sakr <[email protected]>

.github/workflows/github-pages-publishing.yml

@@ -2,7 +2,7 @@ name: update GitHub pages
 
 on:
   push:
-    branches: ["main"]
+    branches: ["stable"]
   workflow_dispatch:
 
 permissions:
@@ -22,6 +22,8 @@ jobs:
     steps:
       - name: checkout
         uses: actions/checkout@v4
+        with:
+          ref: stable
 
       - name: setup pages
         uses: actions/configure-pages@v5