Revert "use timezone of event"

This reverts commit 9662e1f333.

source/includes/LocalDateTime.php

@@ -0,0 +1,15 @@
+<?php
+namespace MobilizonConnector;
+
+final class LocalDateTime {
+  private $dateTime;
+
+  public function __construct(string $text, \DateTimeZone $timeZone) {
+    $date = new \DateTimeImmutable($text);
+    $this->dateTime = $date->setTimezone($timeZone);
+  }
+
+  public function getValue() {
+    return $this->dateTime;
+  }
+}