Remove the "isNot" alias on the HasRoles trait

Laravel (in 5.4.31) added its own "isNot" method to the base Eloquent
Model class. Pull: laravel/framework#20354
So we unfortunately have to remove our alias, which fixes #187.

src/Database/Concerns/HasRoles.php

@@ -109,22 +109,6 @@ public function isNotA($role)
         return call_user_func_array([$this, 'isNotAn'], func_get_args());
     }
 
-    /**
-     * Check if the model has none of the given roles.
-     *
-     * Alias for the "isNotAn" method.
-     *
-     * @param  string  $role
-     * @return bool
-     */
-    public function isNot($role)
-    {
-        return call_user_func_array(
-            [$this, 'isNotAn'],
-            func_get_args()
-        );
-    }
-
     /**
      * Check if the model has all of the given roles.
      *

tests/HasRolesAndAbilitiesTraitTest.php

@@ -145,7 +145,6 @@ public function test_can_check_roles()
         $this->assertFalse($user->isAn('admin'));
 
         $this->assertTrue($user->isNotA('admin'));
-        $this->assertTrue($user->isNot('admin'));
         $this->assertFalse($user->isA('admin'));
 
         $user->assign('admin');
@@ -160,14 +159,12 @@ public function test_can_check_multiple_roles()
     {
         $gate = $this->gate($user = User::create());
 
-        $this->assertTrue($user->isNot('admin', 'editor'));
         $this->assertFalse($user->isAn('admin', 'editor'));
 
         $user->assign('moderator');
         $user->assign('editor');
 
         $this->assertTrue($user->isAn('admin', 'moderator'));
-        $this->assertFalse($user->isNot('admin', 'moderator'));
         $this->assertTrue($user->isAll('editor', 'moderator'));
         $this->assertFalse($user->isAll('moderator', 'admin'));
     }