Use @unique to ensure and communicate enum uniqueness

src/mock_vws/_constants.py

@@ -2,12 +2,13 @@
 Constants used to make the VWS mock.
 """
 
-from enum import Enum
+from enum import Enum, unique
 
 from beartype import beartype
 
 
 @beartype
+@unique
 class ResultCodes(Enum):
     """Constants representing various VWS result codes.
 
@@ -42,6 +43,7 @@ class ResultCodes(Enum):
 
 
 @beartype
+@unique
 class TargetStatuses(Enum):
     """Constants representing VWS target statuses.
 

src/mock_vws/states.py

@@ -2,12 +2,13 @@
 Vuforia database states.
 """
 
-from enum import StrEnum, auto
+from enum import StrEnum, auto, unique
 
 from beartype import beartype
 
 
 @beartype
+@unique
 class States(StrEnum):
     """
     Constants representing various web service states.