Feature/merge 3 0 develop (#298)

* merging 3.0 into develop

* N°5102 - Allow to send emails (eg. notifications) using GSuite SMTP and OAuth
* migration to iTop 3.1

Co-authored-by: Eric Espie <eric.espie@combodo.com>

lib/guzzlehttp/promises/src/AggregateException.php

@@ -0,0 +1,17 @@
+<?php
+
+namespace GuzzleHttp\Promise;
+
+/**
+ * Exception thrown when too many errors occur in the some() or any() methods.
+ */
+class AggregateException extends RejectionException
+{
+    public function __construct($msg, array $reasons)
+    {
+        parent::__construct(
+            $reasons,
+            sprintf('%s; %d rejected promises', $msg, count($reasons))
+        );
+    }
+}