fix reformat cmd (#917)

Co-authored-by: starylan <starylan@outlook.com>

tools/uvr5/webui.py

@@ -73,8 +73,7 @@ def uvr(model_name, inp_root, save_root_vocal, paths, save_root_ins, agg, format
                     os.path.basename(inp_path),
                 )
                 os.system(
-                    "ffmpeg -i %s -vn -acodec pcm_s16le -ac 2 -ar 44100 %s -y"
+                    f'ffmpeg -i "{inp_path}" -vn -acodec pcm_s16le -ac 2 -ar 44100 "{tmp_path}" -y'
-                    % (inp_path, tmp_path)
                 )
                 inp_path = tmp_path
             try: