Update TEST_MAPPING am: 76e56e04a6

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/thiserror/+/2398876

Change-Id: I2b9f56ce6d7eec23bde5128020942807f41f56b1
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>