Ignore needless_late_init Clippy lint in test

    error: unneeded late initalization
      --> tests/test_generics.rs:90:5
       |
    90 |     let mut instance: EnumCompound<DisplayOnly, DebugOnly, NoFormat>;
       |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
       = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_late_init
    help: declare `instance` here
       |
    92 |     let mut instance: EnumCompound<DisplayOnly, DebugOnly, NoFormat> = EnumCompound::DisplayDebug(DisplayOnly, DebugOnly);
       |     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

tests/test_generics.rs

@@ -1,4 +1,5 @@
 #![deny(clippy::all, clippy::pedantic)]
+#![allow(clippy::needless_late_init)]
 
 use std::fmt::{self, Debug, Display};
 use thiserror::Error;