Upgrade half to 2.2.1 am: dc2e05e117 am: 75287a0360 am: c451789e02

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/half/+/2419359

Change-Id: Iecc1d694a24dfb561f460aa9bddde8a6a2a3db59
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>