switch from PyQt6 to PySide6

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

colorbutton.py

@@ -1,12 +1,12 @@
 import re
 
-from PyQt6.QtGui import QColor, QPixmap, QIcon
-from PyQt6.QtWidgets import QWidget, QHBoxLayout, QPushButton, QColorDialog, QSizePolicy, QComboBox
+from PySide6.QtGui import QColor, QPixmap, QIcon
+from PySide6.QtWidgets import QWidget, QHBoxLayout, QPushButton, QColorDialog, QSizePolicy, QComboBox
 
 
 class ColorButton(QWidget):
-    def __init__(self, color: str):
-        super(QWidget, self).__init__()
+    def __init__(self, color: str, parent=None):
+        super(ColorButton, self).__init__(parent)
 
         self.setSizePolicy(QSizePolicy(QSizePolicy.Policy.Fixed, QSizePolicy.Policy.Fixed))
         self.layout = QHBoxLayout(self)