fix: 修复无法正确获取文件后缀名的问题

nc_http/core/file/func.py

@@ -22,7 +22,7 @@ def save_file(f: FileStorage, path: str, namespace: str = None, filename: str =
     if not os.path.exists(save_path):
         os.makedirs(save_path)
 
-    filename = filename or '{}{}'.format(str(int(time.time() * 1000)), os.path.splitext(f.name)[-1])
+    filename = filename or '{}{}'.format(str(int(time.time() * 1000)), os.path.splitext(f.filename)[-1])
     file_path = os.path.join(save_path, filename)
     with open(file_path, 'wb+') as tmp_f:
         tmp_f.write(f.read())