GitHub: Add environment to Format XAML workflow (#14217)

Author: heftymouse

.github/workflows/format-xaml.yml

@@ -7,7 +7,7 @@ jobs:
   format-xaml:
     if: github.event.issue.pull_request && github.event.comment.body == '/format'
     runs-on: ubuntu-latest
-    
+    environment: Pull Requests
     defaults:
       run:
         shell: pwsh