Upgrade fonttools to 4.15.0 am: c9804561ed am: 6baeafbb6d am: 4f502262a1

Original change: https://android-review.googlesource.com/c/platform/external/fonttools/+/1433028

Change-Id: Ie453e47bf7537b6f6016f55f8f921c31db5f3489