fixed warning

src/App.jsx

@@ -22,9 +22,9 @@ function App() {
 
     const toggleLanguage = () => {
         if (i18n.language === 'de') {
-            i18n.changeLanguage('en').then(r => console.log("Changed language to 'en'"));
+            i18n.changeLanguage('en').then(_ => console.log("Changed language to 'en'"));
         } else {
-            i18n.changeLanguage('de').then(r => console.log("Changed language to 'de'"));
+            i18n.changeLanguage('de').then(_ => console.log("Changed language to 'de'"));
         }
     };