Models fix: remove ABC from DataMixin

.gitignore

@@ -3,3 +3,5 @@
 __pycache__
 *.pyc
 .idea
+pyqt6_scaffold.egg-info
+dist

pyqt6_scaffold/core/models.py

@@ -1,6 +1,5 @@
 # SPDX-License-Identifier: LGPL-3.0-or-later
 
-from abc import ABC
 from typing import List, Sequence, Any
 from PyQt6.QtGui import QColor, QBrush, QFont
 from PyQt6.QtCore import (
@@ -11,7 +10,7 @@ from PyQt6.QtCore import (
     QVariant
 )
 
-class DataMixin(ABC):
+class DataMixin:
     """
     Mixin for Qt data models providing common data storage and display logic.