JWTAuth always returns false in Laravel 6

I want to create a Laravel 6 backend with JWT authentication and when I want to sign in a user, JWTAuth always returns false, I google it but can't find any solution for it.

here are my project files codes,

this is my UserController

    <?php

namespace App\Http\Controllers;

use App\Http\Requests\UserRequest;
use App\User;
use Illuminate\Http\Request;
use Tymon\JWTAuth\Exceptions\JWTException;
use Tymon\JWTAuth\Facades\JWTAuth;

class UserController extends Controller
{
    public function signup(Request $request)
    {
        $user = new User();
        $user->name = $request->input('name');
        $user->email = $request->input('email');
        $user->password = $request->input('password');
        $user->save();
        
        return response()->json(['message'=>'User Created Successfully!',$user],201);
    }

    public function signin(Request $request)
    {
        $credentials = [];
        $credentials['email'] = $request->input('email');
        $credentials['password'] = bcrypt($request->input('password'));
        try{
            if(!$token = JWTAuth::attempt($credentials)){
                return response()->json(['error'=>'Invalid Credentials!'],401);
            }
        }catch(JWTException $e){
            return response()->json(['error' => 'Could Not Create Token!'],500);
        }

        return response()->json(['token'=>$token],200);
    }
}

User Model

<?php

namespace App;

use Illuminate\Contracts\Auth\MustVerifyEmail;
use Illuminate\Foundation\Auth\User as Authenticatable;
use Illuminate\Notifications\Notifiable;
use Tymon\JWTAuth\Contracts\JWTSubject;

class User extends Authenticatable implements JWTSubject
{
    use Notifiable;

    /**
     * The attributes that are mass assignable.
     *
     * @var array
     */
    protected $fillable = [
        'name', 'email', 'password',
    ];

    /**
     * The attributes that should be hidden for arrays.
     *
     * @var array
     */
    protected $hidden = [
        'password', 'remember_token',
    ];

    /**
     * The attributes that should be cast to native types.
     *
     * @var array
     */
    protected $casts = [
        'email_verified_at' => 'datetime',
    ];

    /**
     * Get the identifier that will be stored in the subject claim of the JWT.
     *
     * @return mixed
     */
    public function getJWTIdentifier() {
        return $this->getKey();
    }

    /**
     * Return a key value array, containing any custom claims to be added to the JWT.
     *
     * @return array
     */
    public function getJWTCustomClaims() {
        return [];
    }    

    public function setPasswordAttribute($password)
    {
        if ( !empty($password) ) {
            $this->attributes['password'] = bcrypt($password);
        }
    }
}

And Api Route

<?php

use Illuminate\Support\Facades\Route;
/*
|--------------------------------------------------------------------------
| API Routes
|--------------------------------------------------------------------------
|
| Here is where you can register API routes for your application. These
| routes are loaded by the RouteServiceProvider within a group which
| is assigned the "api" middleware group. Enjoy building your API!
|
*/


Route::post('/user','UserController@signup');
Route::post('/user/signin','UserController@signin');

when I want to sign in a user, JWTAuth:attempt($credentials), I don't know what I am missing or wrong? Is there any solution?