Supporting openssl 3.0

[bdescamps]

Currently bitcoin-ruby is not compatible with openssl 3.0

[phlegx]

Following a working hook:

# bitcoin.rb
module Bitcoin
  module Util
    def bitcoin_elliptic_curve
      ::OpenSSL::PKey::EC.generate('secp256k1')
    end

    def generate_key
      key = bitcoin_elliptic_curve
      inspect_key( key )
    end
  end

  class Key
    def generate
      @key
    end
  end
end