Suppress mixed_script_confusables in test suite

error: The usage of Script Group `Greek` in this crate consists solely of mixed script confusables
       --> test_suite/tests/test_gen.rs:269:9
        |
    269 |         σ: f64,
        |         ^
        |
    note: the lint level is defined here
       --> test_suite/tests/test_gen.rs:5:9
        |
    5   | #![deny(warnings)]
        |         ^^^^^^^^
        = note: `#[deny(mixed_script_confusables)]` implied by `#[deny(warnings)]`
        = note: The usage includes 'σ' (U+03C3).
        = note: Please recheck to make sure their usages are indeed what you want.

test_suite/tests/test_gen.rs

@@ -4,7 +4,7 @@
 
 #![deny(warnings)]
 #![cfg_attr(feature = "unstable", feature(non_ascii_idents))]
-#![allow(clippy::trivially_copy_pass_by_ref)]
+#![allow(mixed_script_confusables, clippy::trivially_copy_pass_by_ref)]
 
 use serde::de::DeserializeOwned;
 use serde::{Deserialize, Deserializer, Serialize, Serializer};