BUG : read_json with table='orient' causes unexpected type coercion 
BUG : read_json with table='orient' causes unexpected type coercion #21345

- [x] closes #21345
- [ ] tests added / passed
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry

Changed `.astype` parameters according to the comments. Should work now
