minor symfony#52353 [Yaml] Remove test on Inline::parse(null) (GromNaN)

This PR was merged into the 6.4 branch.

Discussion
----------

[Yaml] Remove test on `Inline::parse(null)`

| Q             | A
| ------------- | ---
| Branch?       | 6.4
| Bug fix?      | yes
| New feature?  | no
| Deprecations? | no
| Issues        | Fix symfony#52334
| License       | MIT

This test was added by symfony#52332
It becomes wrong with symfony#52334
It was not reverted by symfony@eaff34a

Commits
-------

9b10106 Fix wrong yaml parse null test

Author: xabbuh

src/Symfony/Component/Yaml/Tests/InlineTest.php

@@ -318,7 +318,6 @@ public static function getTestsForParse()
     {
         return [
             ['', ''],
-            [null, ''],
             ['null', null],
             ['false', false],
             ['true', true],