Upgrade combine to 4.6.6 am: 8d75b00921 am: 646bede66f am: a5e6f25965

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

Change-Id: I951e21661c793c972ee0d821b1bed7e7856857d4
Signed-off-by: Automerger Merge Worker <[email protected]>