Make ReactAdapter constructor public

This allows using the ReactAdapter separately from Amp's global event loop, e.g. if someone just wants to run their ReactPHP application with UV.

lib/ReactAdapter.php

@@ -16,7 +16,7 @@ class ReactAdapter implements LoopInterface {
     private $writeWatchers = [];
     private $timers = [];
 
-    private function __construct(Driver $driver) {
+    public function __construct(Driver $driver) {
         $this->driver = $driver;
     }