Base concurrency on PR number

Author: stevapple

.github/workflows/generate.yml

@@ -8,7 +8,7 @@ on:
       - 'Sources/**'
       - 'Package.*'
 
-concurrency: codegen-sync
+concurrency: codegen-sync-${{ github.event.number }}
 
 env:
   TECO_BRANCH: codegen-pr-${{ github.event.number }}