New 1.78 clippy warnings in tests

[sdroege]

warning: trait `FooExt` is never used
   --> glib-macros/tests/test.rs:286:19
    |
286 |         pub trait FooExt: IsA<Foo> + 'static {
    |                   ^^^^^^
    |
    = note: `#[warn(dead_code)]` on by default

warning: `glib-macros` (test "test") generated 1 warning
warning: methods `not_overridden`, `connect_overridden_notify`, `connect_not_overridden_notify`, `notify_overridden`, and `notify_not_overridden` are never used
  --> glib-macros/tests/properties.rs:16:18
   |
16 |         #[derive(Properties, Default)]
   |                  ^^^^^^^^^^
17 |         #[properties(wrapper_type = super::Base, ext_trait)]
   |                                            ---- methods in this trait
   |
   = note: `#[warn(dead_code)]` on by default

warning: module has the same name as its containing module
   --> glib-macros/tests/properties.rs:515:5
    |
515 | /     mod empty {
516 | |         mod imp {
517 | |             use glib::subclass::prelude::*;
518 | |             use glib_macros::Properties;
...   |
536 | |         }
537 | |     }
    | |_____^
    |
    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#module_inception
    = note: `#[warn(clippy::module_inception)]` on by default

[bilelmoussaoui]

Can be closed now