Add theme provider to App.ts

src/App.tsx

 import React from 'react';
 import { BrowserRouter as Router } from 'react-router-dom';
 import { ClientContextProvider } from './context';
+import ThemeProvider from './context/ThemeProvider';
 import { UserStateProvider } from './context/UserContext';
 import Routes from './Routes';
 
@@ -8,9 +9,11 @@ function App(): React.ReactElement {
   return (
     <ClientContextProvider>
       <UserStateProvider>
+        <ThemeProvider>
           <Router>
             <Routes />
           </Router>
+        </ThemeProvider>
       </UserStateProvider>
     </ClientContextProvider>
   );