Upgrade rust/crates/regex to 1.4.3

Test: make
Change-Id: I0a2f64e0e7e81dc3e46c5c21ffa0bfbc7b1fb28f
diff --git a/src/lib.rs b/src/lib.rs
index bdcebd4..d3dc58d 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -616,6 +616,7 @@
 #![deny(missing_docs)]
 #![cfg_attr(test, deny(warnings))]
 #![cfg_attr(feature = "pattern", feature(pattern))]
+#![warn(missing_debug_implementations)]
 
 #[cfg(not(feature = "std"))]
 compile_error!("`std` feature is currently required to build this crate");