chore: upgrade wif to v4.0.0

[ChrisCho-H]

update wif following bitcoinjs/wif#30
this will prevent error caused by crypto libs in browser or mobile

[junderw]

I would rather remove wif.

In a BIP32 world, wif is unnecessary.

Even if you need it, you can always do wif.encode(node.privateKey)

[ChrisCho-H]

bip32 has a function toWIF() which has a dependency on wif.
do u think that module is also better to be removed?

[junderw]

Yes, that is what I meant when I said we should remove it.

It would be a breaking change, so I've been putting it off, I should have removed it when we updated for taproot.

[ChrisCho-H]

I made PR #82 to remove wif