Update Rust version to nightly-2026-02-03

Code changes are:
- Removed unnecessary `isize` import.

UI test changes are:
- Showing full paths to more name. A bit unfortunate in our case, since
  some things live inside `__macros`, maybe we should consider changing
  that?
- Fewer repeated mentions of the same unsatisfied trait bound, that's
  nice!
- Removed "this note originates in the macro `assert_eq`", also nice!
- Dyn check swallows other checks earlier, probably nicer in our case.

Assembly test changes are:
- A bit less alignment (?) needed.
- Less code emitted for panics inside drop.
- Reordered stuff in fast enumeration, unsure if for the better or not?
  We might want to add some `#[cold]` annotations.

Author: madsmtm

.github/workflows/ci.yml

@@ -63,7 +63,7 @@ env:
   # END AUTOMATICALLY GENERATED
 
   # The current nightly Rust version. Keep this synced with `rust-toolchain.toml`
-  CURRENT_NIGHTLY: nightly-2025-12-17
+  CURRENT_NIGHTLY: nightly-2026-02-03
   # https://doc.rust-lang.org/cargo/guide/cargo-home.html#caching-the-cargo-home-in-ci
   # Note: We don't cache `~/.cargo/bin`, that is done separately when needed.
   CARGO_CACHE_PATH: |

crates/header-translator/src/library.rs

@@ -1,10 +1,10 @@
 use std::collections::{BTreeMap, BTreeSet};
+use std::fmt;
 use std::fs;
 use std::io::ErrorKind;
 use std::io::Write;
 use std::iter;
 use std::path::Path;
-use std::{fmt, isize};
 
 use toml_edit::InlineTable;
 use toml_edit::{value, Array, DocumentMut, Item, Table, Value};