ci(publish): skip preview publish on forks

Author: rechedev9

.github/workflows/publish.yml

@@ -38,6 +38,7 @@ jobs:
               run: pnpm run build:all
 
             - name: Publish preview packages
+              if: github.repository == 'modelcontextprotocol/typescript-sdk'
               run:
                   pnpm dlx pkg-pr-new publish --packageManager=npm --pnpm './packages/server' './packages/client'
                   './packages/middleware/express' './packages/middleware/hono' './packages/middleware/node'