[TASK] Mark OutputFormatter as @internal

This class should only be used for formatting CSS from
within this library. It is not intended to be called
from outside.

Author: oliverklee

CHANGELOG.md

@@ -21,6 +21,7 @@ Please also have a look at our
 
 ### Changed
 
+- Mark `OutputFormatter` as `@internal` (#896)) 
 - Only allow `string` for some `OutputFormat` properties (#885)
 - Make all non-private properties `@internal` (#886)
 - Use more native type declarations and strict mode

src/OutputFormatter.php

@@ -7,6 +7,9 @@
 use Sabberworm\CSS\Comment\Commentable;
 use Sabberworm\CSS\Parsing\OutputException;
 
+/**
+ * @internal since 8.8.0
+ */
 class OutputFormatter
 {
     /**