Fix test warnings

Apparantely, React Router 7 is going to bring some changes, and people
are encouraged to opt int to those early.

Author: malor

src/components/App.jsx

@@ -41,7 +41,7 @@ const App = () => {
   }
 
   return (
-    <Router>
+    <Router future={{ v7_startTransition: true, v7_relativeSplatPath: true }}>
       <Fragment>
         <Header />
         <div className="content">

tests/components/Sidebar.test.tsx

@@ -5,7 +5,11 @@ import { BrowserRouter } from 'react-router-dom'
 import Sidebar from '../../src/components/Sidebar'
 
 const renderWithRouter = (component: React.ReactElement) => {
-  return render(<BrowserRouter>{component}</BrowserRouter>)
+  return render(
+    <BrowserRouter future={{ v7_startTransition: true, v7_relativeSplatPath: true }}>
+      {component}
+    </BrowserRouter>
+  )
 }
 
 describe('Sidebar', () => {