[aur-requests] [PRQ#12277] Orphan Request for python-isbntools

caleb [1] filed a orphan request for python-isbntools [2]: Like [isbnlib](https://aur.archlinux.org/packages/python-isbnlib) this has been flagged out of date for 5 months. I've adopted and updated the lib, I can do the tools too. [1] https://aur.archlinux.org/account/caleb/ [2] https://aur.archlinux.org/pkgbase/python-isbntools/