修复windows下加载训练好的Promt静态json文件时，报gbk编码错误问题

[turkeymz]

PR types

Bug fixes

PR changes

Models

Description

运行环境：Windows
使用trainer进行prompt训练并保存后相关静态文件后，再使用AutoTemplate.load_from()/SoftVerbalizer.load_from()/PromptTrainer.load_state_dict_from_checkpoint()都无法加载静态文件。
报错原因是保存时规定了utf-8保存，而加载时未限制。导致windows下的gbk编码报错
修复地方：
PromptTrainer引用的是AutoTemplate和SoftVerbalizer，所以只需要修复这两个文件下load_from方法即可

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 53.39%. Comparing base (f8604c4) to head (026aace).
⚠️ Report is 2540 commits behind head on develop.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #5318      +/-   ##
===========================================
- Coverage    53.43%   53.39%   -0.05%     
===========================================
  Files          476      476              
  Lines        67323    67567     +244     
===========================================
+ Hits         35976    36079     +103     
- Misses       31347    31488     +141     

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[turkeymz]

@ZeyuChen 老师，能不能帮忙指导一下这个问题。现在代码写得有点别扭，希望后面版本能改善调

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