minor symfony#50865 [VarDumper] enforce UTC timezone in test (xabbuh)

This PR was merged into the 5.4 branch.

Discussion
----------

[VarDumper] enforce UTC timezone in test

| Q             | A
| ------------- | ---
| Branch?       | 5.4
| Bug fix?      | no
| New feature?  | no
| Deprecations? | no
| Tickets       |
| License       | MIT
| Doc PR        |

This should fix the failing VarDumper tests on AppVeyor.

Commits
-------

5473840 enforce UTC timezone in test

Author: xabbuh

src/Symfony/Component/VarDumper/Tests/Caster/DateCasterTest.php

@@ -25,6 +25,22 @@ class DateCasterTest extends TestCase
 {
     use VarDumperTestTrait;
 
+    private $previousTimezone;
+
+    protected function setUp(): void
+    {
+        parent::setUp();
+
+        $this->previousTimezone = date_default_timezone_get();
+    }
+
+    protected function tearDown(): void
+    {
+        parent::tearDown();
+
+        date_default_timezone_set($this->previousTimezone);
+    }
+
     /**
      * @dataProvider provideDateTimes
      */
@@ -95,6 +111,8 @@ public static function provideDateTimes()
      */
     public function testCastDateTimeNoTimezone($time, $xDate, $xInfos)
     {
+        date_default_timezone_set('UTC');
+
         $stub = new Stub();
         $date = new NoTimezoneDate($time);
         $cast = DateCaster::castDateTime($date, Caster::castObject($date, \DateTime::class), $stub, false, 0);