fix(ci): silence semicolon-in-expressions-from-macros in u256 (#10986)

Newer nightly toolchains flag `uint::construct_uint!`'s internal
macro expansion under this lint, and the docs jobs deny all warnings,
so `cargo doc --all-features --document-private-items` fails to
compile zebra-chain on both the Book workflow and PR CI.

Author: gustavovalverde

zebra-chain/src/work/u256.rs

@@ -5,6 +5,8 @@
 #![allow(clippy::range_plus_one)]
 #![allow(clippy::fallible_impl_from)]
 #![allow(missing_docs)]
+// `uint`'s macro expansion trips this lint on newer nightlies: https://github.com/rust-lang/rust/issues/79813
+#![allow(semicolon_in_expressions_from_macros)]
 
 use uint::construct_uint;