Fix calculating file size

i am incredibly dumb

src/workers.rs

@@ -666,7 +666,7 @@ pub async fn upload_worker(
                     }
                 };
             }
-            let mut size = file.stream_position().await.unwrap();
+            let mut size = total_size - file.stream_position().await.unwrap();
             if size > 2000 * 1024 * 1024 {
                 size = 2000 * 1024 * 1024;
             }