refactor: remove lazy_static crate

The `lazy_static` crate was superseded by the `once_cell` crate which
has been included in Rust's standard library since version `1.70`.
Remove the `lazy_static` dependency and refactor all use cases to use
`std::sync::OnceLock` instead.

Co-authored-by: Henrik Friedrichsen <henrik@affekt.org>

src/main.rs

@@ -3,8 +3,6 @@
 #[macro_use]
 extern crate cursive;
 #[macro_use]
-extern crate lazy_static;
-#[macro_use]
 extern crate serde;
 
 use std::path::PathBuf;