bug #33965 [HttpFoundation] Add plus character + to legal mime subtype (ilzrv)

This PR was merged into the 3.4 branch.

Discussion
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[HttpFoundation] Add plus character `+` to legal mime subtype

| Q             | A
| ------------- | ---
| Branch?       | 3.4
| Bug fix?      | yes
| New feature?  | no
| Deprecations? | no
| Tickets       | -
| License       | MIT
| Doc PR        | -

For example, the following mime type (used for epub) is not recognized given the current regexp: `application/epub+zip; charset=binary`

Commits
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56895f12b9 Add plus character `+` to legal mime subtype

src/Symfony/Component/HttpFoundation/File/MimeType/FileBinaryMimeTypeGuesser.php

@@ -89,7 +89,7 @@ class FileBinaryMimeTypeGuesser implements MimeTypeGuesserInterface
 
         $type = trim(ob_get_clean());
 
-        if (!preg_match('#^([a-z0-9\-]+/[a-z0-9\-\.]+)#i', $type, $match)) {
+        if (!preg_match('#^([a-z0-9\-]+/[a-z0-9\-\+\.]+)#i', $type, $match)) {
             // it's not a type, but an error message
             return null;
         }