Upgrade rust/crates/protobuf-codegen to 2.18.1 am: b62512d3c6

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/protobuf-codegen/+/1510356

Change-Id: Ib1d21a9651f5d664ac2250f42ef1c25257ceb14f