pull the user from the $request (#10169)

the `$user` variable does not exist. we need to retrieve the user via `$request->user()`

Author: browner12

cashier-paddle.md

@@ -1147,7 +1147,8 @@ Once you are ready to create an actual subscription for the user, you may use th
     use Illuminate\Http\Request;
 
     Route::get('/user/subscribe', function (Request $request) {
-        $checkout = $user->subscribe('pri_monthly')
+        $checkout = $request->user()
+            ->subscribe('pri_monthly')
             ->returnTo(route('home'));
 
         return view('billing', ['checkout' => $checkout]);