chore: Release linux-raw-sys version 0.4.0

Author: sunfishcode

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "linux-raw-sys"
-version = "0.4.0-pre.0"
+version = "0.4.0"
 authors = ["Dan Gohman <dev@sunfishcode.online>"]
 description = "Generated bindings for Linux's userspace API"
 documentation = "https://docs.rs/linux-raw-sys"