With the recent update to NUT-08, we can ensure that the amount of blank
outputs is always enough to cover any overpaid lightning fees. This
change implements this functionality for both the wallet and the mint.
The mint updateis backwards-compatible with respect to old wallets.
* fix private key derivation
* add backwards compatilibity for old keysets
* bump version
* test pubkeys and private keys
* make format
* reset keys for tests
* fix cli tests