Replace cargo-cranky with workspace lints (#4413)

Replace `cargo-cranky` (which has served us well) with workspace lints

examples/save_plot/src/main.rs

@@ -1,4 +1,5 @@
 #![cfg_attr(not(debug_assertions), windows_subsystem = "windows")] // hide console window on Windows in release
+#![allow(rustdoc::missing_crate_level_docs)] // it's an example
 
 use eframe::egui;
 use egui_plot::{Legend, Line, Plot, PlotPoints};