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

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

Change-Id: If4abcf2ae17bc9f3cb5c3cdae26ffc204c22ee3e
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>