Merge branch '5.2' into 5.3

* 5.2:
  [Form] fix support for years outside of the 32b range on x86 arch
  Add an upgrade note about the removal of Serializable

Author: nicolas-grekas

Tests/RememberMe/PersistentRememberMeHandlerTest.php

@@ -118,7 +118,7 @@ public function testConsumeRememberMeCookieExpired()
         $this->tokenProvider->expects($this->any())
             ->method('loadTokenBySeries')
             ->with('series1')
-            ->willReturn(new PersistentToken(InMemoryUser::class, 'wouter', 'series1', 'tokenvalue', new \DateTime('-'.(31536000 - 1).' years')));
+            ->willReturn(new PersistentToken(InMemoryUser::class, 'wouter', 'series1', 'tokenvalue', new \DateTime('-'.(31536000 - 1).' seconds')));
 
         $this->tokenProvider->expects($this->never())->method('updateToken')->with('series1');