Add stale control header to statics

index.ts

@@ -28,7 +28,7 @@ const serveStaticHeaders = [
     source: "**/*",
     headers: [{
       key: "Cache-Control",
-      value: "public, max-age: 86400, s-maxage: 86400"
+      value: "public, max-age=86400, s-maxage=86400, stale-while-revalidate=86400"
     }]
   }
 ]