frost-core v2.1.0

• It is now possible to identify the culprit in frost_core::keys::dkg::part3()
  if an invalid secret share was sent by one of the participants (by calling
  frost_core::Error<C>::culprit()) (#728)
• Added frost-secp256k1-tr crate, allowing to generate Bitcoin Taproot
  (BIP340/BIP341) compatible signatures (#730).
• Support refreshing shares using the DKG approach using the
  frost_core::keys::refresh::refresh_dkg_{part1,part2,shares}() functions
  (#766).
• frost_core::keys::dkg::part{1,2}::SecretPackage are now serializable (#833).

Full Changelog: frost-core/v2.0.0...frost-core/v2.1.0