Exclude generated main_window_ui.py from ruff

The pyuic6-generated UI module is regenerated from main_window.ui and is
not meant to be hand-formatted, so exclude it from ruff format/check,
matching the existing how-to-indent sample_code.py exclude.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: realpython-bot

pyproject.toml

@@ -5,7 +5,8 @@ exclude = [
     ".devcontainers",
     ".github",
     "migrations",
-    "how-to-indent-in-python/sample_code.py"
+    "how-to-indent-in-python/sample_code.py",
+    "qt-designer-python/sample_editor/main_window_ui.py"
 ]
 
 [tool.ruff.lint]