Update dependencies and disable unneeded syn feature (#3)

* Update dependencies and disable unneeded syn feature

* Update syn dependency for required features only

Only depend on the required derive, parsing and proc-macro features from
syn.

Prefer to depend on minor versions, rather than patches.

wchar-impl/Cargo.toml

@@ -14,7 +14,11 @@ license = "MIT"
 proc-macro = true
 
 [dependencies]
-proc-macro2 = "0.4"
+proc-macro2 = "1.0"
 proc-macro-hack = "0.5"
-quote = "0.6"
-syn = { version = "0.15", features = ["full"] }
+quote = "1.0"
+
+[dependencies.syn]
+version = "1.0"
+default-features = false
+features = ["derive", "parsing", "proc-macro"]