Set correct header for attach_temporary_file for ServiceDesk (#560)

Author: kilianyp

atlassian/service_desk.py

@@ -432,7 +432,10 @@ def attach_temporary_file(self, service_desk_id, filename):
         url = 'rest/servicedeskapi/servicedesk/{}/attachTemporaryFile'.format(service_desk_id)
 
         with open(filename, 'rb') as file:
-            result = self.post(path=url, headers=self.experimental_headers,
+            headers = {
+                        'X-Atlassian-Token': 'no-check',
+                        'X-ExperimentalApi': 'opt-in'}
+            result = self.post(path=url, headers=headers,
                                files={'file': file}).get('temporaryAttachments')
             temp_attachment_id = result[0].get('temporaryAttachmentId')