Revert "Un-finalize Printer"

This reverts commit 1abeeb7.

Author: ondrejmirtes

build/PHPStan/Build/FinalClassRule.php

@@ -6,7 +6,6 @@
 use PHPStan\Analyser\Scope;
 use PHPStan\File\FileHelper;
 use PHPStan\Node\InClassNode;
-use PHPStan\Node\Printer\Printer;
 use PHPStan\Reflection\FunctionVariant;
 use PHPStan\Reflection\ExtendedFunctionVariant;
 use PHPStan\Reflection\Php\DummyParameter;
@@ -55,7 +54,6 @@ public function processNode(Node $node, Scope $scope): array
 			ExtendedFunctionVariant::class,
 			DummyParameter::class,
 			PhpFunctionFromParserNodeReflection::class,
-			Printer::class,
 		], true)) {
 			return [];
 		}

src/Node/Printer/Printer.php

@@ -22,7 +22,7 @@
 /**
  * @api
  */
-class Printer extends Standard
+final class Printer extends Standard
 {
 
 	public function __construct()