Apply suggestions from code review

Co-authored-by: Sergei Predvoditelev <[email protected]>

src/Column/ColumnFactory.php

@@ -7,7 +7,7 @@
 use Yiisoft\Db\Schema\Column\AbstractColumnFactory;
 use Yiisoft\Db\Schema\SchemaInterface;
 
-class ColumnFactory extends AbstractColumnFactory
+final class ColumnFactory extends AbstractColumnFactory
 {
     /**
      * Mapping from physical column types (keys) to abstract column types (values).