Unable to build on rust version 1.43.0-nightly  #24

use linked_list_allocator::LockedHeap;

error[E0053]: method `alloc` has an incompatible type for trait
   --> /Users/mac/.cargo/registry/src/github.com-1ecc6299db9ec823/linked_list_allocator-0.7.0/src/lib.rs:133:5
    |
133 |     unsafe fn alloc(&mut self, layout: Layout) -> Result<NonNull<u8>, AllocErr> {
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected tuple, found struct `core::ptr::NonNull`
    |
    = note: expected fn pointer `unsafe fn(&mut Heap, core::alloc::Layout) -> core::result::Result<(core::ptr::NonNull<u8>, usize), _>`
               found fn pointer `unsafe fn(&mut Heap, core::alloc::Layout) -> core::result::Result<core::ptr::NonNull<u8>, _>`