Replace #[allow attributes with expect (#7796)

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

crates/epaint/src/text/font.rs

@@ -1,4 +1,4 @@
-#![allow(clippy::mem_forget)]
+#![expect(clippy::mem_forget)]
 
 use emath::{GuiRounding as _, OrderedFloat, Vec2, vec2};
 use self_cell::self_cell;