Update unicode-xid to 0.2

Author: cwfitzgerald

Cargo.toml

@@ -17,7 +17,7 @@ include = ["src/**/*", "Cargo.toml", "README.md", "LICENSE"]
 syn = { version = "1", features = ["visit", "extra-traits"] }
 proc-macro2 = "1"
 quote = "1"
-unicode-xid = "0.1"
+unicode-xid = "0.2"
 
 [dev-dependencies]
 # Used in the documentation as an example trait crate provider. Unfortunately,