BUG: set_precision format fixed (#13257)
- [x] closes #13257
- [x] tests added / passed
- [x] passes `black pandas`
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [x] whatsnew entry

I've tried to fix the set_precision format, does that fix it? 

### INPUT -> df.style.set_precision(2)
| A | B |
| --- | --- |
| 1 | 2.0090 |
| 3.2121 | 4.566 |
### OUTPUT
| A | B |
| --- | --- |
| 1 | 2.01 |
| 3.21 | 4.57 |

@vinigl
@samuelgranato


