Remove PhpParsableStringifier

This stringifier has no much value for a use, and is better to return
NULL than return a PHP parsable code.

Author: henriquemoody

src/Stringifiers/ClusterStringifier.php

@@ -65,7 +65,6 @@ public static function createDefault(): self
             new BoolStringifier($quoter),
             new NullStringifier($quoter),
             new JsonParsableStringifier(),
-            new PhpParsableStringifier(),
         ]);
 
         return $stringifier;