[CS] Fixed outstanding CS issue in ContentTest

Author: alongosz

tests/lib/Repository/Service/Mock/ContentTest.php

@@ -3485,7 +3485,7 @@ static function (SPIValue $value) use ($emptyValue) {
 
         $existingRelations = ['RELATIONS!!!'];
         $repositoryMock->method('sudo')->willReturn($existingRelations);
-        $relationProcessorMock->expects($this->any())
+        $relationProcessorMock->expects(self::any())
             ->method('processFieldRelations')
             ->with(
                 self::isType('array'),