Migrate to cargo_embargo. am: 66e61af4a9 am: fcdd05c154

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/litrs/+/2796436

Change-Id: Iee16d61d58c3a118f93cc893d75ca8356f5d23b1
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>