assume_aligned uses bytes not bits

Reference issue

Fixes #2984 (closed)

What does this implement/fix?

I assumed that the alignment parameter was measured in bits instead of bytes. Because I am a dumbass! Cppref is not clear, but this is: https://open-std.org/JTC1/SC22/WG21/docs/papers/2018/p1007r1.pdf

Additional information