Upgrade python/pybind11 to v2.6.2 am: c1e4e8e441 am: bf74725cfe am: 83a1de439f am: 85b1239953

Original change: https://android-review.googlesource.com/c/platform/external/python/pybind11/+/1561635

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: Ief2ecbfc5c6d91e3b495fbdefeec0b5be0615e07