Update to syn 2. am: 1240985f4b am: 6a7faeac42 am: 5576c54d72

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/asn1-rs-derive/+/2870435

Change-Id: Ibed11fb97d24a707a4368d653bd525ec29fa2b9b
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>