fix: post attachment task not trigger on queue issue

Mastodon/Scene/Compose/ComposeViewModel.swift

@@ -292,11 +292,10 @@ final class ComposeViewModel: NSObject {
             .store(in: &disposeBag)
 
         // setup attribute updater
-        Publishers.CombineLatest(
-            attachmentServices,
-            context.timestampUpdatePublisher
-        )
-        .sink { attachmentServices, _ in
+        attachmentServices
+            .receive(on: DispatchQueue.main)
+            .debounce(for: 0.3, scheduler: DispatchQueue.main)
+            .sink { attachmentServices in
                 // drive service upload state
                 // make image upload in the queue
                 for attachmentService in attachmentServices {