deps: update regex crate

This update brings with it a new feature of the regex crate which will
now use SIMD optimizations automatically at runtime with no necessary
compile time flags. All that's needed is to enable the `unstable` feature.

Other crates, such as bytecount and encoding_rs, are still using the
old-style SIMD support, so we leave the simd-accel and avx-accel features.
However, the binaries we distribute on Github no longer have those
features enabled, which makes them truly portable.

Fixes #135

src/args.rs

@@ -599,7 +599,7 @@ impl<'a> ArgMatches<'a> {
         // This would normally just be an empty string, which works on its
         // own, but if the patterns are joined in a set of alternations, then
         // you wind up with `foo|`, which is invalid.
-        self.word_pattern("z{0}".to_string())
+        self.word_pattern("(?:z{0})*".to_string())
     }
 
     /// Returns true if and only if file names containing each match should