Approval status fix

Author: VaghinakDev

src/superannotate/lib/app/interface/sdk_interface.py

@@ -83,7 +83,7 @@
     "NotStarted", "InProgress", "QualityCheck", "Returned", "Completed", "Skipped"
 ]
 
-APPROVAL_STATUS = Literal["Approved", "Disapproved"]
+APPROVAL_STATUS = Literal["Approved", "Disapproved", None]
 
 IMAGE_QUALITY = Literal["compressed", "original"]
 
@@ -3101,7 +3101,7 @@ def add_items_to_subset(
     def set_approval_statuses(
         self,
         project: NotEmptyStr,
-        approval_status: Union[APPROVAL_STATUS, None],
+        approval_status: APPROVAL_STATUS,
         items: Optional[List[NotEmptyStr]] = None,
     ):
         """Sets annotation statuses of items

src/superannotate/lib/infrastructure/validators.py

@@ -22,7 +22,7 @@ def make_literal_validator(
     Adding ability to input literal in the lower case.
     """
     permitted_choices = validators.all_literal_values(type_)
-    allowed_choices = {v.lower(): v for v in permitted_choices}
+    allowed_choices = {v.lower() if v else v: v for v in permitted_choices}
 
     def literal_validator(v: typing.Any) -> typing.Any:
         try: