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

This PR was merged into the 6.3 branch.

Discussion
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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/LinkedInTransportTest.php

@@ -57,9 +57,7 @@ public function testSendWithEmptyArrayResponseThrowsTransportException()
             ->method('getContent')
             ->willReturn('[]');
 
-        $client = new MockHttpClient(static function () use ($response): ResponseInterface {
-            return $response;
-        });
+        $client = new MockHttpClient(static fn (): ResponseInterface => $response);
 
         $transport = $this->createTransport($client);
 
@@ -82,9 +80,7 @@ public function testSendWithErrorResponseThrowsTransportException()
             ->method('getContent')
             ->willReturn('testErrorCode');
 
-        $client = new MockHttpClient(static function () use ($response): ResponseInterface {
-            return $response;
-        });
+        $client = new MockHttpClient(static fn (): ResponseInterface => $response);
 
         $transport = $this->createTransport($client);
 
@@ -187,9 +183,7 @@ public function testSendWithInvalidOptions()
     {
         $this->expectException(LogicException::class);
 
-        $client = new MockHttpClient(function (string $method, string $url, array $options = []): ResponseInterface {
-            return $this->createMock(ResponseInterface::class);
-        });
+        $client = new MockHttpClient(fn (string $method, string $url, array $options = []): ResponseInterface => $this->createMock(ResponseInterface::class));
 
         $transport = $this->createTransport($client);