Remove duplicate code move to yiisoft/db/Schema::class. (#179)

* Remove duplicate code move to yiisoft/db/Schema::class.

src/Schema.php

@@ -21,7 +21,6 @@
 use Yiisoft\Db\Schema\Schema as AbstractSchema;
 use Yiisoft\Db\Schema\TableSchemaInterface;
 
-use function array_change_key_case;
 use function array_merge;
 use function array_unique;
 use function array_values;
@@ -1081,21 +1080,4 @@ protected function getCacheTag(): string
     {
         return md5(serialize(array_merge([self::class], $this->db->getCacheKey())));
     }
-
-    /**
-     * Changes row's array key case to lower.
-     *
-     * @param array $row row's array or an array of row's arrays.
-     * @param bool $multiple whether multiple rows or a single row passed.
-     *
-     * @return array normalized row or rows.
-     */
-    protected function normalizeRowKeyCase(array $row, bool $multiple): array
-    {
-        if ($multiple) {
-            return array_map(static fn (array $row) => array_change_key_case($row, CASE_LOWER), $row);
-        }
-
-        return array_change_key_case($row, CASE_LOWER);
-    }
 }