Enable the clippy::std_instead_of_core lint (#8394)

Prefer `core::` over `std::` where either work

* Part of https://github.com/emilk/egui/issues/5735

crates/egui_glow/src/shader_version.rs

@@ -2,7 +2,7 @@
 #![expect(clippy::unwrap_used)] // TODO(emilk): avoid unwraps
 #![expect(unsafe_code)]
 
-use std::convert::TryInto as _;
+use core::convert::TryInto as _;
 
 /// Helper for parsing and interpreting the OpenGL shader version.
 #[derive(Copy, Clone, Debug, PartialEq, Eq)]