Issue #3362088 by Lukas von Blarer, mondrake, Berdir: ExtensionMimeTypeGuesser...

Issue #3362088 by Lukas von Blarer, mondrake, Berdir: ExtensionMimeTypeGuesser doesn't support .avif

core/lib/Drupal/Core/File/MimeType/ExtensionMimeTypeGuesser.php

@@ -281,6 +281,7 @@ class ExtensionMimeTypeGuesser implements MimeTypeGuesserInterface {
       251 => 'chemical/x-vmd',
       252 => 'chemical/x-xtel',
       253 => 'chemical/x-xyz',
+      362 => 'image/avif',
       254 => 'image/gif',
       255 => 'image/ief',
       256 => 'image/jpeg',
@@ -864,6 +865,7 @@ class ExtensionMimeTypeGuesser implements MimeTypeGuesserInterface {
       'mjs' => 132,
       'aac' => 360,
       'json' => 361,
+      'avif' => 362,
     ],
   ];