Update to syn-2 am: 971a9d6cf1 am: b6890e6816 am: 883b76d3fa am: 48fc21558e am: 27381885a9 am: 48f46929ae

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/syn-mid/+/2522319

Change-Id: I9c70efc17d499d5a049f69ceb509634e8cf635f3
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>