switch from PyQt6 to PySide6

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

label.py

@@ -1,5 +1,5 @@
-from PyQt6.QtWidgets import QLabel
-from PyQt6.QtCore import Qt
+from PySide6.QtWidgets import QLabel
+from PySide6.QtCore import Qt
 
 
 class Label(QLabel):
@@ -7,4 +7,5 @@ class Label(QLabel):
         super(Label, self).__init__(text)
         self.setTextInteractionFlags(Qt.TextInteractionFlag.TextBrowserInteraction)
         self.setTextInteractionFlags(Qt.TextInteractionFlag.LinksAccessibleByMouse)
+        self.setTextInteractionFlags(Qt.TextInteractionFlag.TextSelectableByMouse)
         self.setOpenExternalLinks(True)