minor #20174 [Serializer] minor: Remove an extra space in a YamlFileL…

…oader error (dunglas)

This PR was squashed before being merged into the 3.1 branch (closes #20174).

Discussion
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[Serializer] minor: Remove an extra space in a YamlFileLoader error

| Q             | A
| ------------- | ---
| Branch?       | 3.1
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | n/a
| License       | MIT
| Doc PR        | n/a

Commits
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a1bc96b [Serializer] minor: Remove an extra space in a YamlFileLoader error

src/Symfony/Component/Serializer/Mapping/Loader/YamlFileLoader.php

@@ -90,7 +90,7 @@ public function loadClassMetadata(ClassMetadataInterface $classMetadata)
 
                     if (isset($data['max_depth'])) {
                         if (!is_int($data['max_depth'])) {
-                            throw new MappingException('The "max_depth" value must an integer  in "%s" for the attribute "%s" of the class "%s".', $this->file, $attribute, $classMetadata->getName());
+                            throw new MappingException('The "max_depth" value must be an integer in "%s" for the attribute "%s" of the class "%s".', $this->file, $attribute, $classMetadata->getName());
                         }
 
                         $attributeMetadata->setMaxDepth($data['max_depth']);