Merge branch '5.0'

* 5.0:
  [Routing] fix tests
  [DI] minor cleanup
  [Form] group constraints when calling the validator
  Remove wrong @group legacy annotations
  [DependencyInjection] Fix dumping multiple deprecated aliases
  allow button names to start with uppercase letter
  Allow PHP ^7.2.5
  States that the HttpClient provides a Http Async implementation
  [Routing] Fix ContainerLoader and ObjectLoaderTest
  [HttpKernel] Make ErrorListener::onKernelException()'s dispatcher argument explicit
  [HttpKernel] Drop deprecated ExceptionListener
  Removed extra whitespace
  [Security] Fix best encoder not wired using migrate_from

Author: nicolas-grekas

composer.json

@@ -15,12 +15,13 @@
         }
     ],
     "provide": {
+        "php-http/async-client-implementation": "*",
         "php-http/client-implementation": "*",
         "psr/http-client-implementation": "1.0",
         "symfony/http-client-implementation": "1.1"
     },
     "require": {
-        "php": "^7.2.9",
+        "php": "^7.2.5",
         "psr/log": "^1.0",
         "symfony/http-client-contracts": "^1.1.8|^2",
         "symfony/polyfill-php73": "^1.11"