Upgrade rust/crates/regex to 1.4.3 am: 47619ddc40 am: b145f3db78 am: be45e3505d

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/regex/+/1544767

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: I526c9aee533eb698d44f69e52e160275d746050d