gpu-burn/common.h missing `<memory>` header

[colleeneb]

Hello,

It looks like std::unique_ptr is used without including the <memory> header. This code worked fine with AMD HIP, but I think it still technically needs the header included. (I found this when trying to compiler with HIPCL, which does need the <memory> header include.)

For example, adding something like: https://github.com/colleeneb/HIP-Examples/blob/f00739a2dd6fe4dca41c1555105d4c332af236a5/gpu-burn/common.h#L9

I can submit a PR if you want, otherwise it's a one-line change so hopefully it's easy to do.

Thanks!