Step all bootstrap cfgs forward

Mark-Simulacrum · Mark-Simulacrum · commit 81eb8a657400 · 2024-02-08T07:44:34.000-05:00
This also takes care of other bootstrap-related changes.
diff --git a/src/lib.rs b/src/lib.rs
@@ -10,7 +10,7 @@
 #![feature(nonzero_ops)]
 #![feature(let_chains)]
 #![feature(lint_reasons)]
-#![cfg_attr(not(bootstrap), feature(trait_upcasting))]
+#![feature(trait_upcasting)]
 // Configure clippy and other lints
 #![allow(
     clippy::collapsible_else_if,
