Update num-traits to 0.2 and bump version

Author: Eijebong

Cargo.toml

@@ -2,7 +2,7 @@
 name = "mozjs"
 description = "Rust bindings to the Mozilla SpiderMonkey JavaScript engine."
 repository = "https://github.com/servo/rust-mozjs"
-version = "0.7.1"
+version = "0.7.2"
 authors = ["The Servo Project Developers"]
 build = "build.rs"
 license = "MPL-2.0"
@@ -46,5 +46,5 @@ promises = ['mozjs_sys/promises']
 lazy_static = "1"
 libc = "0.2"
 log = "0.4"
-num-traits = "0.1.32"
+num-traits = "0.2"
 mozjs_sys = "0.51.1"