Fix compiling on nightly

[kerosina]

In nightly, the compiler complains about:

error[E0059]: type parameter to bare `Fn` trait must be a tuple
   --> C:\Users\[redacted]\.cargo\registry\src\index.crates.io-6f17d22bba15001f\detour-0.8.1\src\detours\statik.rs:106:8
    |
106 |     D: Fn<T::Arguments, Output = T::Output> + Send + 'static,
    |        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `Tuple` is not implemented for `<T as Function>::Arguments`
    |
note: required by a bound in `Fn`
   --> C:\Users\[redacted]\.rustup\toolchains\nightly-x86_64-pc-windows-msvc\lib/rustlib/src/rust\library\core\src\ops\function.rs:76:20
    |
76  | pub trait Fn<Args: Tuple>: FnMut<Args> {
    |                    ^^^^^ required by this bound in `Fn`
help: consider further restricting the associated type
    |
106 |     D: Fn<T::Arguments, Output = T::Output> + Send + 'static, <T as Function>::Arguments: Tuple
    |                                                             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The rust core lib's Fn trait was updated to constrain Args to have the Tuple trait.
This PR follows the suggestions of the compiler and fixes the issue by adding a bound to T::Arguments where it must also have Tuple.