minor #48793 Leverage arrow function syntax for closure (tigitz)

This PR was merged into the 6.3 branch.

Discussion
----------

Leverage arrow function syntax for closure

| Q             | A
| ------------- | ---
| Branch?       | 6.3
| Bug fix?      | no
| New feature?  | no <!-- please update src/**/CHANGELOG.md files -->
| Deprecations? | no <!-- please update UPGRADE-*.md and src/**/CHANGELOG.md files -->
| Tickets       | Fix #47658 <!-- prefix each issue number with "Fix #", no need to create an issue if none exists, explain below instead -->
| License       | MIT
| Doc PR        | <!-- required for new features -->

Rationale in the RFC [here](https://wiki.php.net/rfc/arrow_functions_v2#introduction)

It's also notable that using arrow function syntax rather than the classic one has been enforced in the past by symfony core member: symfony/symfony#48069 (comment)

So this PR would be consistent.

Commits
-------

f5802d3a2a Leverage arrow function syntax for closure

Author: nicolas-grekas

Tests/Command/MailerTestCommandTest.php

@@ -30,14 +30,10 @@ public function testSendsEmail()
         $mailer
             ->expects($this->once())
             ->method('send')
-            ->with(self::callback(static function (Email $message) use ($from, $to, $subject, $body): bool {
-                return
-                    $message->getFrom()[0]->getAddress() === $from &&
-                    $message->getTo()[0]->getAddress() === $to &&
-                    $message->getSubject() === $subject &&
-                    $message->getTextBody() === $body
-                ;
-            }))
+            ->with(self::callback(static fn (Email $message): bool => $message->getFrom()[0]->getAddress() === $from &&
+            $message->getTo()[0]->getAddress() === $to &&
+            $message->getSubject() === $subject &&
+            $message->getTextBody() === $body))
         ;
 
         $tester = new CommandTester(new MailerTestCommand($mailer));
@@ -57,9 +53,7 @@ public function testUsesCustomTransport()
         $mailer
             ->expects($this->once())
             ->method('send')
-            ->with(self::callback(static function (Email $message) use ($transport): bool {
-                return $message->getHeaders()->getHeaderBody('X-Transport') === $transport;
-            }))
+            ->with(self::callback(static fn (Email $message): bool => $message->getHeaders()->getHeaderBody('X-Transport') === $transport))
         ;
 
         $tester = new CommandTester(new MailerTestCommand($mailer));

Transport/AbstractApiTransport.php

@@ -39,8 +39,6 @@ protected function doSendHttp(SentMessage $message): ResponseInterface
 
     protected function getRecipients(Email $email, Envelope $envelope): array
     {
-        return array_filter($envelope->getRecipients(), function (Address $address) use ($email) {
-            return false === \in_array($address, array_merge($email->getCc(), $email->getBcc()), true);
-        });
+        return array_filter($envelope->getRecipients(), fn (Address $address) => false === \in_array($address, array_merge($email->getCc(), $email->getBcc()), true));
     }
 }

Transport/AbstractTransport.php

@@ -112,9 +112,7 @@ abstract protected function doSend(SentMessage $message): void;
      */
     protected function stringifyAddresses(array $addresses): array
     {
-        return array_map(function (Address $a) {
-            return $a->toString();
-        }, $addresses);
+        return array_map(fn (Address $a) => $a->toString(), $addresses);
     }
 
     protected function getLogger(): LoggerInterface