Upgrade either to 1.8.1 am: 8eae190e5a am: 370b3a19c6

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/either/+/2438852

Change-Id: I911cfba209d10b3c8692bc026cafa402e3a83a5e
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>