Update heapsize dependency.

[jdm]

This change is 

[kvark]

Is it an implementation detail? I'd assume that since the public types implement heapsize trait and they are visible, then the dependency is also public-visible, and thus should bump the minor package version.

[jdm]

No aspect of the HeapSizeOf trait changed, and this crate does not reexport the pieces of heapsize that did change.

[kvark]

@jdm

No aspect of the HeapSizeOf trait changed

The trait itself is technically different. Supposing the user code has that:

extern crate euclid; //version 0.12.0
extern crate heapsize; //version 0.3
use heapsize::HeapSizeOf;

fn foo<T, U>(length: euclid::Length<T, U>) -> usize {
  length.heap_size_of_children()
}

This works. Now the user does cargo update -p euclid, gets version 0.12.1, and suddenly their code breaks because the imported HeapSizeOf doesn't match euclid's HeapSizeOf.

[jdm]

I am convinced.

[kvark]

Thanks! Do you mind squashing it?
r=me

[jdm]

@bors-servo: r=kvark

[bors-servo]

📌 Commit 72bc87c has been approved by kvark

[bors-servo]

⌛ Testing commit 72bc87c with merge 16ee6fc...

[bors-servo]

☀️ Test successful - status-travis
Approved by: kvark
Pushing 16ee6fc to master...