Update to syn-2 am: 06ea9e5af4 am: 01485df57e

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/bindgen/+/2520775

Change-Id: I49f539be3e3fe2787c8a81690f8e9935afe00a49
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>