[mypy] Add mypy type annotation part 1 (#4006)

vllm/executor/neuron_executor.py

@@ -1,4 +1,4 @@
-from typing import Dict, List, Optional
+from typing import Dict, List, Optional, Tuple
 
 from vllm.config import (CacheConfig, DeviceConfig, LoRAConfig, ModelConfig,
                          ParallelConfig, SchedulerConfig, SpeculativeConfig,
@@ -47,7 +47,7 @@ class NeuronExecutor(ExecutorBase):
         self.driver_worker.init_device()
         self.driver_worker.load_model()
 
-    def determine_num_available_blocks(self) -> tuple[int, int]:
+    def determine_num_available_blocks(self) -> Tuple[int, int]:
         """Determine the number of available KV blocks by invoking the
         underlying worker.
         """