Fix transitions query schema to indicate it returns a list (#12967)

* Fix transitions query schema to indicate it returns a list

* Update api version

* Update api_version.py

---------

Co-authored-by: Matthias Mair <code@mjmair.com>

src/backend/InvenTree/InvenTree/api_version.py

@@ -1,11 +1,14 @@
 """InvenTree API version information."""
 
 # InvenTree API version
-INVENTREE_API_VERSION = 551
+INVENTREE_API_VERSION = 552
 """Increment this API version number whenever there is a significant change to the API that any clients need to know about."""
 
 INVENTREE_API_TEXT = """
 
+v552 -> 2026-10-02 : https://github.com/inventree/InvenTree/pull/12967
+    - Fix transitions endpoint schema to indicate that it returns a list
+
 v551 -> 2026-09-21 : https://github.com/inventree/InvenTree/pull/12693
     - Docstring updates for automated transition API documentation generation
     - New transitions insights endpoints

src/backend/InvenTree/generic/states/api_helpers.py

@@ -355,12 +355,15 @@ class FSMTransitionMixin:
             if getattr(handler, 'transition_name', None)
         }
 
+    @extend_schema(responses={200: AvailableTransitionSerializer(many=True)})
     @action(
         detail=True,
         methods=['get'],
         url_path=TRANSITION_URL_PREFIX,
         url_name='transitions',
         serializer_class=AvailableTransitionSerializer,
+        pagination_class=None,
+        filter_backends=[],
     )
     def transitions(self, request: Request, pk: str | None = None, *kwargs) -> Response:
         """List the FSM transitions reachable from this object's current state.