fixed some linting issues

lightrag/api/lightrag_server.py

@@ -26,6 +26,8 @@ from contextlib import asynccontextmanager
 from starlette.status import HTTP_403_FORBIDDEN
 import pipmaster as pm
 
+from dotenv import load_dotenv
+
 
 def get_default_host(binding_type: str) -> str:
     default_hosts = {
@@ -39,9 +41,6 @@ def get_default_host(binding_type: str) -> str:
     )  # fallback to ollama if unknown
 
 
-from dotenv import load_dotenv
-
-
 def get_env_value(env_key: str, default: Any, value_type: type = str) -> Any:
     """
     Get value from environment variable with type conversion
@@ -58,7 +57,7 @@ def get_env_value(env_key: str, default: Any, value_type: type = str) -> Any:
     if value is None:
         return default
 
-    if value_type == bool:
+    if isinstance(value_type, bool):
         return value.lower() in ("true", "1", "yes")
     try:
         return value_type(value)