Merge branch '5.4' into 6.0

* 5.4:
  [Messenger] Use :memory: for SQLite tests
  [Mailer] Stream timeout not detected due to checking only string result of function fgets
  don not set http_version instead of setting it to null
  [DependencyInjection] don't move locator tag for service subscriber
  Fix search scope when performing fallback mapping driver detection
  Fix the notification email theme for asynchronously dispatched emails
  Update the CI setup to use the new output file
  Update actions in the CI to move away from the deprecated runtime
  Use 6.3 for new features
  [HttpFoundation] Check IPv6 is valid before comparing it
  Run tests with UTC to avoid daylight saving time messing with assertions
  Bump Symfony version to 5.4.16
  Update VERSION for 5.4.15
  Update CHANGELOG for 5.4.15
  Bump Symfony version to 4.4.49
  Update VERSION for 4.4.48
  Update CONTRIBUTORS for 4.4.48
  Update CHANGELOG for 4.4.48
  [DependencyInjection] Don't autoconfigure tag when it's already set with attributes

Tests/Transport/DoctrineIntegrationTest.php

@@ -28,23 +28,17 @@ class DoctrineIntegrationTest extends TestCase
     private $driverConnection;
     /** @var Connection */
     private $connection;
-    /** @var string */
-    private $sqliteFile;
 
     protected function setUp(): void
     {
-        $this->sqliteFile = sys_get_temp_dir().'/symfony.messenger.sqlite';
-        $dsn = getenv('MESSENGER_DOCTRINE_DSN') ?: 'sqlite:///'.$this->sqliteFile;
+        $dsn = getenv('MESSENGER_DOCTRINE_DSN') ?: 'sqlite://:memory:';
         $this->driverConnection = DriverManager::getConnection(['url' => $dsn]);
         $this->connection = new Connection([], $this->driverConnection);
     }
 
     protected function tearDown(): void
     {
         $this->driverConnection->close();
-        if (file_exists($this->sqliteFile)) {
-            @unlink($this->sqliteFile);
-        }
     }
 
     public function testConnectionSendAndGet()