Upgrade to 2021 edition

Author: djc

Cargo.toml

@@ -5,7 +5,7 @@ version = "0.15.10"
 keywords = ["cli", "terminal", "colors", "console", "ansi"]
 authors = ["Armin Ronacher <[email protected]>"]
 license = "MIT"
-edition = "2018"
+edition = "2021"
 homepage = "https://github.com/console-rs/console"
 repository = "https://github.com/console-rs/console"
 documentation = "https://docs.rs/console"