0.8.0 breaks word on apostrophe

The behavior change from 0.7.2 to 0.8.0 seems wrong to me:

### in 0.8.0
```
from uniseg.wordbreak import words

list(words("don't"))
['don', "'", 't']  # <-------
list(words("don’t"))
['don’t']
```

### in 0.7.2
```
from uniseg.wordbreak import words

list(words("don't"))
["don't"]

list(words("don’t"))
['don’t']
```
