hw plugins: adapt trezor_qt_pinmatrix.py to qt6

This fixes the pinmatrix dialog (used by trezor one, keepkey, safet),
which was previously segfaulting.

follow-up https://github.com/spesmilo/electrum/pull/9189

electrum/plugins/trezor/qt.py

@@ -14,6 +14,7 @@ from electrum.plugin import hook
 from electrum.keystore import ScriptTypeNotSupported
 
 from electrum.plugins.hw_wallet.qt import QtHandlerBase, QtPluginBase
+from electrum.plugins.hw_wallet.trezor_qt_pinmatrix import PinMatrixWidget
 from electrum.plugins.hw_wallet.plugin import only_hook_if_libraries_available, OutdatedHwFirmwareException
 
 from electrum.gui.qt.util import (WindowModalDialog, WWLabel, Buttons, CancelButton,
@@ -462,7 +463,6 @@ class Plugin(TrezorPlugin, QtPlugin):
 
     @classmethod
     def pin_matrix_widget_class(self):
-        from trezorlib.qt.pinmatrix import PinMatrixWidget
         return PinMatrixWidget
 
     @hook