[CI/Build] mypy: Resolve some errors from checking vllm/engine (#9267)

Signed-off-by: Russell Bryant <rbryant@redhat.com>

vllm/config.py

@@ -626,13 +626,14 @@ class CacheConfig:
         self.sliding_window = sliding_window
         self.enable_prefix_caching = enable_prefix_caching
         self.cpu_offload_gb = cpu_offload_gb
+
         self._verify_args()
         self._verify_cache_dtype()
         self._verify_prefix_caching()
 
         # Will be set after profiling.
-        self.num_gpu_blocks = None
-        self.num_cpu_blocks = None
+        self.num_gpu_blocks: Optional[int] = None
+        self.num_cpu_blocks: Optional[int] = None
 
     def metrics_info(self):
         # convert cache_config to dict(key: str, value: str) for prometheus
@@ -709,7 +710,8 @@ class TokenizerPoolConfig:
 
     @classmethod
     def create_config(
-        cls, tokenizer_pool_size: int, tokenizer_pool_type: str,
+        cls, tokenizer_pool_size: int,
+        tokenizer_pool_type: Union[str, Type["BaseTokenizerGroup"]],
         tokenizer_pool_extra_config: Optional[Union[str, dict]]
     ) -> Optional["TokenizerPoolConfig"]:
         """Create a TokenizerPoolConfig from the given parameters.
@@ -1544,7 +1546,7 @@ class LoRAConfig:
     max_loras: int
     fully_sharded_loras: bool = False
     max_cpu_loras: Optional[int] = None
-    lora_dtype: Optional[torch.dtype] = None
+    lora_dtype: Optional[Union[torch.dtype, str]] = None
     lora_extra_vocab_size: int = 256
     # This is a constant.
     lora_vocab_padding_size: ClassVar[int] = 256