Fix clippy::needless_update warnings

src/theme.rs

@@ -383,7 +383,6 @@ mod tests {
                         theme: ThemePreference::Fixed(ThemeName::Named("Theme".to_string())),
                         theme_dark: Some(ThemeName::Named("Dark Theme".to_string())),
                         theme_light: Some(ThemeName::Named("Light Theme".to_string())),
-                        ..Default::default()
                     },
                 ] {
                     let detector = ConstantDetector(color_scheme);