271191b130efc38ca9da51d1f44a796bf3a95dab Release 7.0.0 (Dr Maxim Orlovsky)

Pull request description:

  Rename SigHash* into Sighash accross the repo

  Reproducible with automatic case-sensetive search/replace

  Make taproot leaf script depth to be u8 everywhere

  I have changed the release notes title from 7.0.0-rc.2 to 7.0.0.

ACKs for top commit:
  apoelstra:
    ACK 271191b130efc38ca9da51d1f44a796bf3a95dab

Tree-SHA512: c77bddaef4ac0862be9920c1d65a6abf2e67226b3b18ce9f873ddfa33d2889427fb05f29cf31174b00fe2849ee84ddb006f8e8632b3ba4497abaf42e66d1fe75