fix(cargo): Update aster, quasi, and syntex

serde_macros/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "serde_macros"
-version = "0.5.3"
+version = "0.6.1"
 authors = ["Erick Tryzelaar <erick.tryzelaar@gmail.com>"]
 license = "MIT/Apache-2.0"
 description = "Macros to auto-generate implementations for the serde framework"
@@ -16,6 +16,6 @@ plugin = true
 serde_codegen = { version = "*", path = "../serde_codegen", default-features = false, features = ["nightly"] }
 
 [dev-dependencies]
-num = "*"
-rustc-serialize = "*"
+num = "^0.1.27"
+rustc-serialize = "^0.3.16"
 serde = { version = "*", path = "../serde", features = ["nightly"] }