Explicitly specify send type for AsyncGenerator

The docs suggest specifying a send type is optional, but recent FastAPI errors if it's not there. This fixes the error and does not change any code.

Author: rwb27

src/labthings_fastapi/outputs/blob.py

@@ -730,7 +730,7 @@ def attach_to_app(self, app: FastAPI) -> None:
 
 async def blob_serialisation_context_manager(
     request: Request,
-) -> AsyncGenerator[BlobDataManager]:
+) -> AsyncGenerator[BlobDataManager, None]:
     r"""Set context variables to allow blobs to be [de]serialised.
 
     In order to serialise a `.Blob` to a JSON-serialisable dictionary, we must

src/labthings_fastapi/server/__init__.py

@@ -241,7 +241,7 @@ def _attach_things_to_server(self) -> None:
             thing.attach_to_server(self)
 
     @asynccontextmanager
-    async def lifespan(self, app: FastAPI) -> AsyncGenerator[None]:
+    async def lifespan(self, app: FastAPI) -> AsyncGenerator[None, None]:
         """Manage set up and tear down of the server and Things.
 
         This method is used as a lifespan function for the FastAPI app. See