Upgrade rust/crates/regex-syntax to 0.6.22

Test: make
Change-Id: I4979a9897fa2edeb552d795b067abcdd6036de0a
diff --git a/Cargo.toml b/Cargo.toml
index f4b1476..0420a2f 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -12,7 +12,7 @@
 
 [package]
 name = "regex-syntax"
-version = "0.6.21"
+version = "0.6.22"
 authors = ["The Rust Project Developers"]
 description = "A regular expression parser."
 homepage = "https://github.com/rust-lang/regex"