Fix Windows build (#8186)

Co-authored-by: Mehrdad <noreply@github.com>

src/ray/core_worker/core_worker.h

@@ -705,7 +705,7 @@ class CoreWorker : public rpc::CoreWorkerServiceHandler {
   /// Implements gRPC server handler.
   void HandleCancelTask(const rpc::CancelTaskRequest &request,
                         rpc::CancelTaskReply *reply,
-                        rpc::SendReplyCallback send_reply_callback);
+                        rpc::SendReplyCallback send_reply_callback) override;
 
   /// Implements gRPC server handler.
   void HandlePlasmaObjectReady(const rpc::PlasmaObjectReadyRequest &request,

src/ray/core_worker/task_manager.h

@@ -135,7 +135,7 @@ class TaskManager : public TaskFinisherInterface, public TaskResubmissionInterfa
   ///
   /// \param[in] task_id to cancel.
   /// \return Whether the task was pending and was marked for cancellation.
-  bool MarkTaskCanceled(const TaskID &task_id);
+  bool MarkTaskCanceled(const TaskID &task_id) override;
 
   /// Return the spec for a pending task.
   absl::optional<TaskSpecification> GetTaskSpec(const TaskID &task_id) const;