Merge branch '5.0' into 5.1

* 5.0: (28 commits)
  [Cache] $lifetime cannot be null
  [Serializer] minor cleanup
  fix merge
  Run PHP 8 as 7.4.99
  Remove calls to deprecated ReflectionParameter::getClass().
  [VarDumper] fix PHP 8 support
  Add php 8 to travis.
  [Cache] Accessing undefined constants raises an Error in php8
  [Cache] allow DBAL v3
  Skip Doctrine DBAL on php 8 until we have a compatible version.
  [DomCrawler] Catch expected ValueError.
  Made method signatures compatible with their corresponding traits.
  [ErrorHandler] Apply php8 fixes from Debug component.
  [DomCrawler] Catch expected ValueError.
  [Validator] Catch expected ValueError.
  [VarDumper] ReflectionFunction::isDisabled() is deprecated.
  [BrowserKit] Raw body with custom Content-Type header
  [PropertyAccess] Parse php 8 TypeErrors correctly.
  [Intl] Fix call to ReflectionProperty::getValue() for static properties.
  [HttpKernel] Prevent calling method_exists() with non-string values.
  ...

bin/simple-phpunit.php

@@ -197,7 +197,7 @@
         $passthruOrFail("$COMPOSER require --no-update phpunit/phpunit-mock-objects \"~3.1.0\"");
     }
 
-    if (preg_match('{\^(\d++\.\d++)[\d\.]*$}', $info['requires']['php'], $phpVersion) && version_compare($phpVersion[1], PHP_VERSION, '<')) {
+    if (preg_match('{\^((\d++\.)\d++)[\d\.]*$}', $info['requires']['php'], $phpVersion) && version_compare($phpVersion[2].'99', PHP_VERSION, '<')) {
         $passthruOrFail("$COMPOSER config platform.php \"$phpVersion[1].99\"");
     } else {
         $passthruOrFail("$COMPOSER config --unset platform.php");