grad_scale is too small
* incorporate https://github.com/k2-fsa/icefall/pull/1269 * incorporate https://github.com/k2-fsa/icefall/pull/1301 * black formatted * incorporate https://github.com/k2-fsa/icefall/pull/1162 * black formatted
* merge upstream * initial commit for zipformer_ctc * remove unwanted changes * remove changes to other recipe * fix zipformer softlink * fix for JIT export * add missing file * fix symbolic links * update results * Update RESULTS.md Address comments from @csukuangfj --------- Co-authored-by: zr_jin <peter.jin.cn@gmail.com>