Allow scalar values for Query::select() (#329)

* Update tests according main PR

* Add type string to test

---------

Co-authored-by: Sergei Predvoditelev <sergei@predvoditelev.ru>

tests/QueryBuilderTest.php

@@ -653,4 +653,10 @@ public function testUpsertExecute(
     ): void {
         parent::testUpsertExecute($table, $insertColumns, $updateColumns);
     }
+
+    /** @dataProvider \Yiisoft\Db\Mysql\Tests\Provider\QueryBuilderProvider::selectScalar */
+    public function testSelectScalar(array|bool|float|int|string $columns, string $expected): void
+    {
+        parent::testSelectScalar($columns, $expected);
+    }
 }