Updated password client to not use client secret in token request

Author: dash8x

tests/Feature/OAuthControllerTest.php

@@ -46,7 +46,6 @@ public function test_it_can_generate_a_password_grant_access_token_for_an_admin(
 
         $this->json('post', '/oauth/token', [
             'client_id' => $client->id,
-            'client_secret' => $client->plainSecret,
             'grant_type' => 'password',
             'username' => $user->email,
             'password' => 'password',
@@ -74,7 +73,6 @@ public function test_it_wont_grant_a_password_access_token_for_an_admin_with_inc
 
         $this->json('post', '/oauth/token', [
             'client_id' => $client->id,
-            'client_secret' => $client->plainSecret,
             'grant_type' => 'password',
             'username' => $user->email,
             'password' => 'wrong password',