keystore.sign_message: add optional script_type argument

this is used by trezor
(and also by bitbox02, which was using a workaround previously)

fixes https://github.com/spesmilo/electrum/issues/7670

electrum/plugins/digitalbitbox/digitalbitbox.py

@@ -455,7 +455,7 @@ class DigitalBitbox_KeyStore(Hardware_KeyStore):
         raise RuntimeError(_('Encryption and decryption are currently not supported for {}').format(self.device))
 
 
-    def sign_message(self, sequence, message, password):
+    def sign_message(self, sequence, message, password, *, script_type=None):
         sig = None
         try:
             message = message.encode('utf8')