minor #14005 CS: Convert double quotes to single quotes (keradus)

This PR was merged into the 2.3 branch.

Discussion
----------

CS: Convert double quotes to single quotes

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | N/A
| License       | MIT
| Doc PR        | N/A

Changes generated automatically by upcoming PHP CS Fixer.
To keep fabbot.io happy ;)

Commits
-------

f99c22c CS: Convert double quotes to single quotes

Author: fabpot

Tests/Extension/Core/EventListener/FixUrlProtocolListenerTest.php

@@ -18,7 +18,7 @@ class FixUrlProtocolListenerTest extends \PHPUnit_Framework_TestCase
 {
     public function testFixHttpUrl()
     {
-        $data = "www.symfony.com";
+        $data = 'www.symfony.com';
         $form = $this->getMock('Symfony\Component\Form\Test\FormInterface');
         $event = new FormEvent($form, $data);
 
@@ -30,7 +30,7 @@ public function testFixHttpUrl()
 
     public function testSkipKnownUrl()
     {
-        $data = "http://www.symfony.com";
+        $data = 'http://www.symfony.com';
         $form = $this->getMock('Symfony\Component\Form\Test\FormInterface');
         $event = new FormEvent($form, $data);
 
@@ -42,7 +42,7 @@ public function testSkipKnownUrl()
 
     public function testSkipOtherProtocol()
     {
-        $data = "ftp://www.symfony.com";
+        $data = 'ftp://www.symfony.com';
         $form = $this->getMock('Symfony\Component\Form\Test\FormInterface');
         $event = new FormEvent($form, $data);
 

Tests/Extension/Core/EventListener/TrimListenerTest.php

@@ -18,7 +18,7 @@ class TrimListenerTest extends \PHPUnit_Framework_TestCase
 {
     public function testTrim()
     {
-        $data = " Foo! ";
+        $data = ' Foo! ';
         $form = $this->getMock('Symfony\Component\Form\Test\FormInterface');
         $event = new FormEvent($form, $data);
 

Tests/Extension/Csrf/EventListener/CsrfValidationListenerTest.php

@@ -62,7 +62,7 @@ protected function getMockForm()
     // https://github.com/symfony/symfony/pull/5838
     public function testStringFormData()
     {
-        $data = "XP4HUzmHPi";
+        $data = 'XP4HUzmHPi';
         $event = new FormEvent($this->form, $data);
 
         $validation = new CsrfValidationListener('csrf', $this->csrfProvider, 'unknown', 'Invalid.');