Bump the edition since why not

SUPERCILEX · SUPERCILEX · commit cf25e4b004e9 · 2022-12-03T12:19:46.000-08:00
Signed-off-by: Alex Saveau &lt;saveau.alexandre@gmail.com&gt;
diff --git a/Cargo.toml b/Cargo.toml
@@ -1,7 +1,7 @@
 [package]
 name        = "nix"
 description = "Rust friendly bindings to *nix APIs"
-edition     = "2018"
+edition     = "2021"
 version     = "0.26.1"
 rust-version = "1.63"
 authors     = ["The nix-rust Project Developers"]
