Remove dependency on memoffset

[syberant]

Description

Hi, I may or may not have used your crate but I'd like to say a quick thank you for it anyway!
I'm going down the list of reverse dependencies on memoffset.

This PR aims to remove the memoffset crate from your dependencies.
core::mem::offset_of was stabilised in rustc 1.77 which I believe is at or below your MSRV.

The memoffset crate 0.9.1 says that

If you're using a rustc version greater or equal to 1.77,
this crate's offset_of!() macro simply forwards to core::mem::offset_of!().

I consider it very unlikely (see here) for any usage of the offset_of! macro to break but please check anyway.
I hope we can all enjoy the benefits of one less dependency :)

Related Issue(s)

N/A

Review Guidance

None

Screenshots/GIFs

N/A

Checklist

• My code follows the project's code style guidelines (I ran cargo fmt)
• I have commented my code, particularly in hard-to-understand areas
• I have updated the documentation accordingly (N/A?)
• My changes don't generate new warnings or errors
• No unsafe code introduced (or if introduced, thoroughly justified and documented)