fix: accept avatars with image/vnd.microsoft.icon mime types

The mime type image/x-icon is not registered with the IANA. Instead,
image/vnd.microsoft.icon is the preferred mime type for .ico files.

Signed-off-by: Richard Steinmetz <[email protected]>

lib/Service/AvatarService.php

@@ -78,6 +78,7 @@ private function hasAllowedMime(Avatar $avatar): bool {
 					'image/jpeg',
 					'image/png',
 					'image/x-icon',
+					'image/vnd.microsoft.icon',
 				]);
 		} else {
 			// We trust internal URLs by default