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/Transport/ConnectionTest.php

@@ -175,9 +175,7 @@ public function testAck()
 
         $client = $this->createMock(PheanstalkInterface::class);
         $client->expects($this->once())->method('useTube')->with($tube)->willReturn($client);
-        $client->expects($this->once())->method('delete')->with($this->callback(function (JobId $jobId) use ($id): bool {
-            return $jobId->getId() === $id;
-        }));
+        $client->expects($this->once())->method('delete')->with($this->callback(fn (JobId $jobId): bool => $jobId->getId() === $id));
 
         $connection = new Connection(['tube_name' => $tube], $client);
 
@@ -194,9 +192,7 @@ public function testAckWhenABeanstalkdExceptionOccurs()
 
         $client = $this->createMock(PheanstalkInterface::class);
         $client->expects($this->once())->method('useTube')->with($tube)->willReturn($client);
-        $client->expects($this->once())->method('delete')->with($this->callback(function (JobId $jobId) use ($id): bool {
-            return $jobId->getId() === $id;
-        }))->willThrowException($exception);
+        $client->expects($this->once())->method('delete')->with($this->callback(fn (JobId $jobId): bool => $jobId->getId() === $id))->willThrowException($exception);
 
         $connection = new Connection(['tube_name' => $tube], $client);
 
@@ -212,9 +208,7 @@ public function testReject()
 
         $client = $this->createMock(PheanstalkInterface::class);
         $client->expects($this->once())->method('useTube')->with($tube)->willReturn($client);
-        $client->expects($this->once())->method('delete')->with($this->callback(function (JobId $jobId) use ($id): bool {
-            return $jobId->getId() === $id;
-        }));
+        $client->expects($this->once())->method('delete')->with($this->callback(fn (JobId $jobId): bool => $jobId->getId() === $id));
 
         $connection = new Connection(['tube_name' => $tube], $client);
 
@@ -231,9 +225,7 @@ public function testRejectWhenABeanstalkdExceptionOccurs()
 
         $client = $this->createMock(PheanstalkInterface::class);
         $client->expects($this->once())->method('useTube')->with($tube)->willReturn($client);
-        $client->expects($this->once())->method('delete')->with($this->callback(function (JobId $jobId) use ($id): bool {
-            return $jobId->getId() === $id;
-        }))->willThrowException($exception);
+        $client->expects($this->once())->method('delete')->with($this->callback(fn (JobId $jobId): bool => $jobId->getId() === $id))->willThrowException($exception);
 
         $connection = new Connection(['tube_name' => $tube], $client);