Migrate to cargo_embargo. am: b6e9f2e4a4

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/regex-syntax/+/2821942

Change-Id: I4c6a9f3e3c44f28b40b325fa75bc67525e118838
Signed-off-by: Automerger Merge Worker <[email protected]>