Upgrade rust/crates/which to 4.2.5 am: d9d261bae5 am: 7663b7b515

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/which/+/2066750

Change-Id: Ib305418bae9e55acf80825931e89b05aed40165f
Signed-off-by: Automerger Merge Worker <[email protected]>