Fixed typo in unit test introduced by accident in e0c61de

Author: hostep

app/code/Magento/Catalog/Test/Unit/Model/Category/Attribute/Backend/SortbyTest.php

@@ -45,7 +45,6 @@ class SortbyTest extends TestCase
      */
     protected function setUp(): void
     {
-        $this->markTestSkipped('Due to MAGETWO-48956');
         $this->objectHelper = new ObjectManager($this);
         $this->scopeConfig = $this->getMockForAbstractClass(ScopeConfigInterface::class);
         $this->model = $this->objectHelper->getObject(
@@ -217,7 +216,7 @@ public function testValidateUnique(): void
     {
         $this->attribute->expects($this->any())->method('getName')->willReturn('attribute_name');
         $this->attribute->method('getIsRequired');
-        $this->attribute§('getIsUnique')
+        $this->attribute->method('getIsUnique')
             ->willReturn(true);
 
         $entityMock = $this->getMockForAbstractClass(