### What problem does this PR solve?
When model’s group name contains 0-9，we can't find downloaded
model，because we do not correctly exstract model dir's name from model‘s
full name
### Type of change
- [ ] Bug Fix (non-breaking change which fixes an issue)
Co-authored-by: 王志鹏 <zhipeng3.wang@midea.com>
Co-authored-by: Kevin Hu <kevinhu.sh@gmail.com>
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