Replace #[allow attributes with expect (#7796)

We do have `clippy::allow_attributes` turned on, but it doesn't seem to
work properly

crates/egui_glow/src/painter.rs

@@ -1,6 +1,5 @@
-#![allow(clippy::collapsible_else_if)]
-#![allow(clippy::unwrap_used)]
-#![allow(unsafe_code)]
+#![expect(clippy::unwrap_used)]
+#![expect(unsafe_code)]
 
 use std::{collections::HashMap, sync::Arc};