remove test-dependencies in favor of native go

[thaJeztah]

Apparently I had this in my local checkout, but never committed or pushed it 😂. Don't know where I left off, but it seems to be complete 🤷‍♂️

[thaJeztah]

To be fair. the "diff" (actual/expected) may be a bit wonky 😅 - let me know if that's a problem

[crazy-max]

Yeah a bit, do you have an issue with transitive deps on another repo?

[thaJeztah]

Not directly, so I'm fine waiting with this. I think I originally looked at what it was used for, and all seemed "trivial enough to not need a dependency for that", but now looking again, the reason I didn't push may have been because of this specific case.

I'll give it some thinking (perhaps we can only add go-cmp (e.g.)