Fix reusable-workflow reference to @main

Author: TingwenZhang

.github/workflows/check-news-item.yml

@@ -7,6 +7,6 @@ on:
 
 jobs:
   check-news-item:
-    uses: Billingegroup/release-scripts/.github/workflows/_check-news-item.yml@v0
+    uses: Billingegroup/release-scripts/.github/workflows/_check-news-item.yml@main
     with:
       project: diffpy.pdfgui