Add-on crashes on startup

[kerimyalcin95]

The add-on crashes when starting. I have disabled all add-ons prior opening and restarted Anki multiple times.

Anki 24.11 (87ccd24e)  (ao)
Python 3.9.18 Qt 6.6.2 PyQt 6.6.1
Platform: Windows-10-10.0.26100

Traceback (most recent call last):
  File "C:\Users\agx\AppData\Roaming\Anki2\addons21\188442097\__init__.py", line 22, in main
    dialog = MainWindow.Dialog(parent)
  File "C:\Users\agx\AppData\Roaming\Anki2\addons21\188442097\MainWindow.py", line 40, in __init__
    self.intro.setAlignment(Qt.AlignCenter)
AttributeError: type object 'Qt' has no attribute 'AlignCenter'

===Add-ons (active)===
(add-on provided name [Add-on folder, installed at, version, is config changed])
Note Comparer ['188442097', 2021-09-17T17:40, 'None', '']

===IDs of active AnkiWeb add-ons===
188442097

===Add-ons (inactive)===
(add-on provided name [Add-on folder, installed at, version, is config changed])
Auto-refresh browser ['746398558', 2024-10-01T14:50, 'None', '']
Better Progress Stats ['301495874', 2024-10-01T01:52, 'None', '']
Editor Live Preview ['1960039667', 2024-03-05T00:59, 'None', '']
FSRS Helper Postpone  Advance  Load Balance  Easy Days  Disperse Siblings ['759844606', 2025-01-24T07:29, 'None', '']
Field AutoComplete ['511710206', 2025-01-29T08:01, 'None', mod]
Show Duplicates Shortcut ['689277073', 2022-11-05T02:58, 'None', mod]```

[wh-ge]

An upgrade from pyqt5 to pyqt6 is required.

[wh-ge]

My pull request includes the necessary changes for the problem.