prevent issues with timezones and DST by using only UNIX timestamps

Author: xabbuh

Tests/RememberMe/PersistentRememberMeHandlerTest.php

@@ -124,7 +124,7 @@ public function testConsumeRememberMeCookieExpired()
         $this->tokenProvider->expects($this->any())
             ->method('loadTokenBySeries')
             ->with('series1')
-            ->willReturn(new PersistentToken(InMemoryUser::class, 'wouter', 'series1', 'tokenvalue', new \DateTime('-'.(31536000 + 1).' seconds')));
+            ->willReturn(new PersistentToken(InMemoryUser::class, 'wouter', 'series1', 'tokenvalue', new \DateTime('@'.(time() - (31536000 + 1)))));
 
         $this->tokenProvider->expects($this->never())->method('updateToken')->with('series1');