Remove tutorial window workaround

[csparker247]

#6 introduces a workaround to a bug in Qt that caused the app to crash when the tutorial window is opened and closed multiple times. We need to remove the workaround when the bug is fixed.

• Connect btn_box.accepted to self.accept instead of self.hide
• Remove the TutorialWindow.closeEvent() function override
• Require PyQt 6.6.2+

[csparker247]

This has been fixed upstream and will be available starting in Qt 6.5.5, 6.6.2, and 6.7+.