BUG: astype falsely converts inf to integer, patch for Numpy (GH14265)
- [x] closes #14265
- [x] tests added / passed
- [x] passes `git diff upstream/master | flake8 --diff`
- [x] whatsnew entry

Bug in Numpy causes inf values to be falsely converted to integers. I added a ValueError exception similar to the exception for trying to convert NaN to an integer. 
