Fix linting errors in the main code

novelwriter/extensions/switchbox.py

@@ -23,8 +23,9 @@ along with this program. If not, see <https://www.gnu.org/licenses/>.
 """
 from __future__ import annotations
 
+from typing import TYPE_CHECKING
+
 from PyQt6.QtCore import pyqtSignal
-from PyQt6.QtGui import QIcon
 from PyQt6.QtWidgets import QGridLayout, QLabel, QScrollArea, QWidget
 
 from novelwriter.extensions.switch import NSwitch
@@ -33,6 +34,9 @@ from novelwriter.types import (
     QtSizeMinimumExpanding
 )
 
+if TYPE_CHECKING:
+    from PyQt6.QtGui import QIcon
+
 
 class NSwitchBox(QScrollArea):
     """Extension: Switch Box Widget