Fix model version in news article generator workflow

Signed-off-by: James Pether Sörling <pethers@users.noreply.github.com>

Author: pethers

.github/workflows/news-article-generator.md

@@ -52,7 +52,7 @@ steps:
 
 engine:
   id: copilot
-  model: claude-opus-4-6
+  model: claude-opus-4.6
 ---
 
 # 📰 News Article Generator Agent