added fix for puli and php 7.3

Author: Nyholm

spec/autoload.php

@@ -2,7 +2,7 @@
 $loader = require __DIR__.'/../vendor/autoload.php';
 
 // Temporary fix for Puli
-if (PHP_VERSION_ID >= 50600) {
+if (PHP_VERSION_ID >= 50600 && PHP_VERSION_ID < 70300) {
     $loader->addClassMap([
         'Puli\\GeneratedPuliFactory' => __DIR__.'/../.puli/GeneratedPuliFactory.php',
     ]);