Remove unnecessary PartialReflect bound on DeserializeWithRegistry

[aecsocket]

Objective

The new DeserializeWithRegistry trait in 0.15 was designed to be used with reflection, and so has a trait DeserializeWithRegistry: PartialReflect bound. However, this bound is not actually necessary for the trait to function properly. And this PartialReflect bound already exists on:

impl<T: PartialReflect + for<'de> DeserializeWithRegistry<'de>> FromType<T>
    for ReflectDeserializeWithRegistry

So there is no point in constraining the trait itself with this bound as well.

This lets me use DeserializeWithRegistry with non-Reflect types, which I want to do to avoid making a bunch of FooDeserializer structs and impl DeserializeSeed on them.

Solution

Removes this unnecessary bound.

Testing

Trivial change, does not break compilation or bevy_reflect tests.

Migration Guide

DeserializeWithRegistry types are no longer guaranteed to be PartialReflect as well. If you were relying on this type bound, you should add it to your own bounds manually.

- impl<T: DeserializeWithRegistry> Foo for T { .. }
+ impl<T: DeserializeWithRegistry + PartialReflect> Foo for T { .. }

[alice-i-cecile]

This makes sense and I trust the compiler here.