remove wildcard version dependency

Author: swizard0

Cargo.toml

@@ -1,7 +1,7 @@
 [package]
 
 name = "simple-signal"
-version = "1.0.2"
+version = "1.0.3"
 authors = ["Antti Keränen <detegr@gmail.com>", "Alexey Voznyuk <me@swizard.info"]
 license = "MIT"
 keywords = ["signal", "SIGINT", "SIGTERM", "SIGQUIT", "SIGABRT"]
@@ -13,7 +13,7 @@ repository = "https://github.com/swizard0/rust-simple-signal.git"
 name = "simple_signal"
 
 [dependencies]
-libc = "*"
+libc = "0.2"
 
 [dependencies.lazy_static]
 version = "0.1"