Remove "inline" as valid attachment type

Author: smartilabs

src/Part.php

@@ -299,7 +299,7 @@ private function parseEncoding(){
      * @return bool
      */
     public function isAttachment(){
-        if ($this->type == IMAP::MESSAGE_TYPE_TEXT && ($this->ifdisposition == 0 || (empty($this->disposition) || !in_array(strtolower($this->disposition), ['attachment', 'inline'])) ) ) {
+        if ($this->type == IMAP::MESSAGE_TYPE_TEXT && ($this->ifdisposition == 0 || (empty($this->disposition) || !in_array(strtolower($this->disposition), ['attachment'])) ) ) {
             if (($this->subtype == null || in_array((strtolower($this->subtype)), ["plain", "csv", "html"])) && $this->filename == null && $this->name == null) {
                 return false;
             }