fix crash when uploading images/videos using external signer

app/src/main/java/com/vitorpamplona/amethyst/ui/actions/NewPostViewModel.kt

@@ -322,6 +322,7 @@ open class NewPostViewModel() : ViewModel() {
                             createNIP95Record(it.readBytes(), contentType, alt, sensitiveContent, relayList = relayList)
                         }
                     } else {
+                        viewModelScope.launch(Dispatchers.IO) {
                             ImageUploader.uploadImage(
                                 uri = fileUri,
                                 contentType = contentType,
@@ -345,6 +346,7 @@ open class NewPostViewModel() : ViewModel() {
                                 }
                             )
                         }
+                    }
                 },
                 onError = {
                     isUploadingImage = false