[mypy][5/N] Support all typing on model executor (#4427)

vllm/model_executor/layers/quantization/__init__.py

@@ -1,4 +1,4 @@
-from typing import Type
+from typing import Dict, Type
 
 from vllm.model_executor.layers.quantization.aqlm import AQLMConfig
 from vllm.model_executor.layers.quantization.awq import AWQConfig
@@ -9,7 +9,7 @@ from vllm.model_executor.layers.quantization.gptq import GPTQConfig
 from vllm.model_executor.layers.quantization.marlin import MarlinConfig
 from vllm.model_executor.layers.quantization.squeezellm import SqueezeLLMConfig
 
-QUANTIZATION_METHODS = {
+QUANTIZATION_METHODS: Dict[str, Type[QuantizationConfig]] = {
     "aqlm": AQLMConfig,
     "awq": AWQConfig,
     "fp8": Fp8Config,