Gedit 48.0 compatibility

[yochananmarqos]

I'm testing 48.alpha from the latest upstream commit:

/usr/lib/gedit/plugins/snippets/substitutionparser.py:162: SyntaxWarning: invalid escape sequence '\s'
  match = re.match('\\\\?%s\s*' % self.REG_GROUP, tokens)
Traceback (most recent call last):
  File "/home/yochanan/.local/share/gedit/plugins/ex-mortis/__init__.py", line 330, in on_app_window_added
    self.setup_window(window)
  File "/home/yochanan/.local/share/gedit/plugins/ex-mortis/__init__.py", line 224, in setup_window
    window_manager.track_window(window)
  File "/home/yochanan/.local/share/gedit/plugins/ex-mortis/windowmanager.py", line 94, in track_window
    state.save_window(window)
  File "/home/yochanan/.local/share/gedit/plugins/ex-mortis/windowstate.py", line 169, in save_window
    self.save_bottom_panel_page_name(window)
  File "/home/yochanan/.local/share/gedit/plugins/ex-mortis/windowstate.py", line 757, in save_bottom_panel_page_name
    page_name = bottom_panel.get_visible_child_name()
                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
AttributeError: 'PanelSimple' object has no attribute 'get_visible_child_name'