Merge branch '6.2' into 6.3

* 6.2:
  [Cache] fix trying to load Memcached before checking we can
  add missing variable
  [Notifier] Make `TransportTestCase` data providers static
  Fix PHPUnit 9.6 deprecations
  [Notifier] Add missing use statement
  [Security] fix compat with security-core v6
  use proper methods to assert exception messages contain certain strings
  Fix tests
  replace usages of the deprecated PHPUnit getMockClass() method
  [gha] Fix high-deps to run with Symfony 6+
  Fix PHPDoc (wrong order)

Author: nicolas-grekas

Tests/Transport/NativeTransportFactoryTest.php

@@ -47,7 +47,7 @@ function ini_get(\$key)
     public function testCreateWithNotSupportedScheme()
     {
         $this->expectException(UnsupportedSchemeException::class);
-        $this->expectErrorMessageMatches('#The ".*" scheme is not supported#');
+        $this->expectExceptionMessage('The "sendmail" scheme is not supported');
 
         $sut = new NativeTransportFactory();
         $sut->create(Dsn::fromString('sendmail://default'));