Add concurrency group for website publish (#1510)

Summary:
Pull Request resolved: https://github.com/facebook/yoga/pull/1510

Make each workflow acquire a shared mutex so that if two commits happen close to each other, the publish order must correspond to commit order.

Reviewed By: cortinico

Differential Revision: D52031970

fbshipit-source-id: 960cd8e8f79b26ab3d9c131e0637b795618d898e

.github/workflows/publish-website.yml

@@ -6,6 +6,9 @@ on:
       - main
   workflow_dispatch:
 
+concurrency:
+  group: ${{ github.workflow }}
+
 jobs:
   publish:
     name: Publish to GitHub Pages