Update to syn-2 am: 50ea5033df am: 797f383cc0 am: cfb9b2a11a am: 4ca6ddea6d am: 5f7a800ce1 am: 53ce7c4db0

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/derive_arbitrary/+/2521017

Change-Id: Id6d07893b65b46e30c4c8ba54ad9df8d0890d315
Signed-off-by: Automerger Merge Worker <[email protected]>