`private_key_debug_is_obfuscated` test is in the wrong crate

[Kixunil]

This test belongs to secp256k1, not bitcoin. The current situation is fragile and annoying.

[tcharding]

We can probably delete the tests if rust-bitcoin/rust-secp256k1#722 merges.

[mahmudsudo]

can i take on this issue ?

[diogocanut]

We can probably delete the tests if rust-bitcoin/rust-secp256k1#722 merges.

It looks like the PR has been merged, so now it's just a matter of removing private_key_debug_is_obfuscated?

[apoelstra]

Yep, let's do it.

[shinghim]

Looks like this is can be closed - fixed by #3517

[tcharding]

Thanks man, its rad that you notice these things.

[shinghim]

@tcharding It's a byproduct of me combing through issues for ones that I can help out on without too much hand holding/review iterations since I don't have much experience in this repo yet. Happy to help! 😄