Use fs_err in more places (#926)
Before:
```
error: Failed to download distributions
Caused by: Failed to fetch wheel: jaxlib==0.4.23+cuda12.cudnn89
Caused by: Directory not empty (os error 39)
```
After:
```
error: Failed to download distributions
Caused by: Failed to fetch wheel: jaxlib==0.4.23+cuda12.cudnn89
Caused by: failed to rename file from /home/konsti/.cache/puffin/.tmpcG7tVP/jaxlib-0.4.23+cuda12.cudnn89-cp310-cp310-manylinux2014_x86_64.whl to /home/konsti/.cache/puffin/wheels-v0/index/9ff50b883297fa9d/jaxlib/jaxlib-0.4.23+cuda12.cudnn89-cp310-cp310-manylinux2014_x86_64
Caused by: Directory not empty (os error 39)
```
