GuiSettings: suppress ClassCanBeRecord inspection

Class GuiSettings cannot be converted into a record at this time due to
lack of support for records in Gson library, which is used for
serialization and deserialization to/from JSON.
google/gson#1794
So mark it with @SuppressWarnings annotation to make the code green in
IntelliJ IDEA.

src/main/java/dev/andrybak/resoday/settings/gui/GuiSettings.java

@@ -12,6 +12,7 @@
 import java.nio.file.Paths;
 import java.util.Objects;
 
+@SuppressWarnings("ClassCanBeRecord") // cannot be a record due to Gson limitations
 public final class GuiSettings {
 	public static final GuiSettings DEFAULT = new GuiSettings(CalendarLayoutSetting.COLUMNS_SIMONE_GIERTZ);
 	private static final Path GUI_SETTINGS_FILE = Paths.get("gui_settings.json");