Upgrade fonttools to 4.18.1 am: 13f9df0298 am: d6972fc726

Original change: https://android-review.googlesource.com/c/platform/external/fonttools/+/1522558

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: I7fac4e47a4456582342c8e51f0d872a94cf771fc