Making MTurk agent approve idempotent (#445)

* Making MTurk agent approve idempotent

* Also edit reject

mephisto/abstractions/providers/mturk/mturk_agent.py

@@ -81,12 +81,18 @@ def new_from_provider_data(
 
     def approve_work(self) -> None:
         """Approve the work done on this specific Unit"""
+        if self.get_status() == AgentState.STATUS_APPROVED:
+            logging.info(f"Approving already approved agent {self}, skipping")
+            return
         client = self._get_client()
         approve_work(client, self._get_mturk_assignment_id(), override_rejection=True)
         self.update_status(AgentState.STATUS_APPROVED)
 
     def reject_work(self, reason) -> None:
         """Reject the work done on this specific Unit"""
+        if self.get_status() == AgentState.STATUS_APPROVED:
+            logging.warning(f"Cannot reject {self}, it is already approved")
+            return
         client = self._get_client()
         reject_work(client, self._get_mturk_assignment_id(), reason)
         self.update_status(AgentState.STATUS_REJECTED)