Benchmark for vek is broken on latest nightly

[utensil]

After bypassing #35, cargo bench --features scalar scalar results in the following compile errors:

error[E0076]: SIMD vector's only field must be an array
    --> ~/.cargo/registry/src/index.crates.io-6f17d22bba15001f/vek-0.15.10/src/vec.rs:3209:13
     |
3209 |             pub struct Vec2<T> { pub x:T, pub y:T }
     |             ^^^^^^^^^^^^^^^^^^   ------- not an array
...
3709 |     vec_impl_all_vecs!{simd #[repr(simd)] c #[repr(C)] repr_simd}
     |     ------------------------------------------------------------- in this macro invocation
     |
     = note: this error originates in the macro `vec_impl_all_vecs` (in Nightly builds, run with -Z macro-backtrace for more info)

This is reported as yoanlcq/vek#96 , there are discussions about fixing this, and a workaround is also provided in the issue, namely:

[dependencies.vek]
version = "0.15.10"
default-features = false
features = ["mint"]
optional = true

i.e. disable default features. The above compiles, but I guess this would have performance impact.