minor #19940 [Yaml] Port of #19922 for 3.2 (chalasr)

This PR was merged into the 3.2-dev branch.

Discussion
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[Yaml] Port of #19922 for 3.2

| Q             | A
| ------------- | ---
| Branch?       | master
| Tests pass?   | yes
| License       | MIT

The command has been moved in 3.2 so the new path is unmerged.

Commits
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017e88b [Yaml] Port of #19922 for 3.2

src/Symfony/Component/Yaml/Command/LintCommand.php

@@ -148,7 +148,7 @@ EOF
             }
         });
 
-        $io->writeln(json_encode($filesInfo, JSON_PRETTY_PRINT));
+        $io->writeln(json_encode($filesInfo, JSON_PRETTY_PRINT | JSON_UNESCAPED_SLASHES));
 
         return min($errors, 1);
     }