Fix “Can't update account settings without setting a bio”

Signed-off-by: Marcin Mikołajczak <me@m4sk.in>

app/Http/Controllers/SettingsController.php

@@ -22,7 +22,7 @@ class SettingsController extends Controller
     {
       $this->validate($request, [
         'name'  => 'required|string|max:30',
-        'bio'   => 'string|max:125'
+        'bio'   => 'nullable|string|max:125'
       ]);
 
       $changes = false;