tostring->tobytes
- [x] closes #33238
- [ ] tests added / passed
- [ ] passes `black pandas`
- [ ] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry

Thanks, maybe a few others

```
pandas/core/computation/pytables.py
176:        val = v.tostring(self.encoding)
606:    def tostring(self, encoding) -> str:

pandas/io/sas/sas.pyx
434:                    start + lngt)]).tostring().rstrip(b"\x00 ")

pandas/_libs/writers.pyx
115:    return narr.tostring().decode('utf-8')
``` updated+green Thanks! @Meeseeksdev backport to 1.0.x

