chore: Enable rust-2024-compatibility lints

Accept the new rules for the `expr` fragment specifier in declarative
macros.

Author: jan-ferdinand

twenty-first/Cargo.toml

@@ -53,6 +53,10 @@ serde_json = "1.0"
 sha3 = "^0.10.8"
 thiserror = "2.0"
 
+[lints.rust]
+edition-2024-expr-fragment-specifier = "allow" # accept the new `expr` fragment specifier rules
+rust-2024-compatibility = "warn"
+
 [[bench]]
 name = "tip5"
 harness = false

twenty-first/src/math/zerofier_tree.rs

@@ -122,7 +122,7 @@ mod test {
         points: Vec<BFieldElement>,
     ) {
         let zerofier_tree = ZerofierTree::new_from_domain(&points);
-        let ZerofierTree::Branch(ref branch) = &zerofier_tree else {
+        let ZerofierTree::Branch(ref branch) = zerofier_tree else {
             panic!("not enough leafs");
         };
         prop_assert_eq!(

twenty-first/src/util_types/merkle_tree.rs

@@ -187,7 +187,7 @@ impl MerkleTree {
     fn authentication_structure_node_indices(
         num_leafs: usize,
         leaf_indices: &[usize],
-    ) -> Result<impl ExactSizeIterator<Item = usize>> {
+    ) -> Result<impl ExactSizeIterator<Item = usize> + use<>> {
         // The set of indices of nodes that need to be included in the authentications
         // structure. In principle, every node of every authentication path is needed.
         // The root is never needed. Hence, it is not considered below.