Use vk::Format that matches coloredCubeData in DynamicUniform RAII sample

[xbohdan]

Hi! The samples in this repository are a gem to anyone learning Vulkan.
I stumbled upon a subtle logical error.
The chosen vk::Format in the DynamicUniform RAII sample does not match coloredCubeData, which results in some information about color being discarded.
The corresponding sample from the vk namespace uses the correct format.
Since these code snippets carry educational purpose, we should fix this issue to avoid confusion.

[CLAassistant]

All committers have signed the CLA.

[asuessenbach]

Thanks for spotting this issue. And fixing it directly!