1.5.6 - upgrade redox_syscall to 0.2

Cargo.toml

 [package]
 name = "termion"
-version = "1.5.5"
+version = "1.5.6"
 authors = ["ticki <Ticki@users.noreply.github.com>", "gycos <alexandre.bury@gmail.com>", "IGI-111 <igi-111@protonmail.com>"]
 description = "A bindless library for manipulating terminals."
 repository = "https://gitlab.redox-os.org/redox-os/termion"
@@ -10,11 +10,11 @@ keywords = ["tty", "color", "terminal", "password", "tui"]
 exclude = ["target", "CHANGELOG.md", "image.png", "Cargo.lock"]
 
 [dependencies]
-numtoa = { version = "0.1.0", features = ["std"]}
+numtoa = { version = "0.1", features = ["std"]}
 
 [target.'cfg(not(target_os = "redox"))'.dependencies]
-libc = "0.2.8"
+libc = "0.2"
 
 [target.'cfg(target_os = "redox")'.dependencies]
-redox_syscall = "0.1"
+redox_syscall = "0.2"
 redox_termios = "0.1"