Upgrade combine to 4.6.6 am: 8d75b00921 am: 646bede66f

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/combine/+/2335682

Change-Id: Ie2587f6ce1192bc9f6abbffbbd809c5d5fb3ff00
Signed-off-by: Automerger Merge Worker <[email protected]>