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

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

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: I77e1fcff93ad84b792bb511bcfb7d993b3ff94b4