Disable compiler warning for Rust 2021 expr fragment specifiers

A manual audit of the existing expr specifiers didn't turn up any problems
with just switching to the 2024 semantics.

https://doc.rust-lang.org/nightly/edition-guide/rust-2024/macro-fragment-specifiers.html

Author: bgilbert

Cargo.toml

@@ -117,6 +117,7 @@ unexpected_cfgs = { level = "warn", check-cfg = ["cfg(tarpaulin_include)"] }
 # absolute_paths_not_starting_with_crate - group rust_2018_compatibility
 # box-pointers - used in project, and is safe to do so
 deprecated_in_future = "warn"
+edition_2024_expr_fragment_specifier = "allow"
 # elided_lifetimes_in_paths - group: rust_2018_idioms
 # explicit_outlives_requirements - group: rust_2018_idioms
 ffi_unwind_calls = "warn"