switch from PyQt6 to PySide6

PySide6 uses LGPL instead of GPL, which is much nicer to work with.

raven/plugins/openfileplugin.py

@@ -1,8 +1,7 @@
 import os
 from typing import Callable
 from pathlib import Path
-from PyQt6.QtGui import QAction, QIcon
-from PyQt6.QtWidgets import QMenu, QFileDialog
+from PySide6.QtWidgets import QFileDialog
 
 from raven.pluginbase import PluginBase
 from raven.pluginregistry import PluginRegistry
@@ -47,8 +46,9 @@ class OpenFilePlugin(PluginBase):
         dialog = QFileDialog()
         (selected_file, _filter) = dialog.getOpenFileName(
             caption=self.tr("Open File"),
-            directory=directory
+            dir=directory
         )
+        # directory=directory
         if selected_file:
             self.open_file(selected_file)
 
@@ -71,7 +71,7 @@ class OpenFilePlugin(PluginBase):
         files = self._get_recent_files()
         for file in files:
             action = RAction(os.path.basename(file))
-            action.set_action(lambda x, f=file: self.open_file(f))
+            action.set_action(lambda _="", f=file: self.open_file(f))
             self._menu_recent_files.add_action(action)
 
     def _remember_recent_file(self, file: str):