Remove MongoSaver date patching

It's already there by xhgui-collector 1.7.0:

- perftools/xhgui-collector#11

composer.json

@@ -27,7 +27,7 @@
 	},
 	"require": {
 		"php": "^5.3.0 || ^7.0 || ^8.0",
-		"perftools/xhgui-collector": "^1.1.0"
+		"perftools/xhgui-collector": "^1.8"
 	},
 	"suggest": {
 		"ext-mongo": "mongo extension (PHP>=5.3,<7.0)",

src/Saver/MongoSaver.php

@@ -18,18 +18,4 @@ public function isSupported()
 
         return class_exists('MongoClient');
     }
-
-    public function save(array $data)
-    {
-        $this->convertTimestamps($data['meta']);
-
-        return parent::save($data);
-    }
-
-    private function convertTimestamps(array &$meta)
-    {
-        $ts = $meta['request_ts_micro'];
-        $meta['request_ts'] = new MongoDate($ts['sec']);
-        $meta['request_ts_micro'] = new MongoDate($ts['sec'], $ts['usec']);
-    }
 }