Fix get current theme (#1959)

selectedTheme was checked only for the value of 'dark', which is why it was not possible to set the Light Theme forcibly and each page overload returned it to dark.

src/utils.ts

@@ -165,7 +165,7 @@ const THEME_STORAGE_KEY = 'z2m-theme';
 export const getCurrentTheme = (): Theme => {
     const prefersDark = window.matchMedia('(prefers-color-scheme: dark)').matches;
     const selectedTheme = local.get(THEME_STORAGE_KEY);
-    return selectedTheme === 'dark' ? 'dark' : (prefersDark ? 'dark' : 'light');
+    return ['light', 'dark'].includes(selectedTheme) ? selectedTheme : (prefersDark ? 'dark' : 'light');
 };
 export const saveCurrentTheme = (theme: string): void => {
     console.log('save', theme);