fix experimental imports (#10875)

libs/experimental/langchain_experimental/synthetic_data/__init__.py

@@ -1,14 +1,12 @@
-from typing import TYPE_CHECKING, Any, Dict, List, Optional
+from typing import Any, Dict, List, Optional
 
+from langchain.chains.base import Chain
 from langchain.chains.llm import LLMChain
+from langchain.prompts import PromptTemplate
+from langchain.schema.language_model import BaseLanguageModel
 
 from langchain_experimental.synthetic_data.prompts import SENTENCE_PROMPT
 
-if TYPE_CHECKING:
-    from langchain.chains.base import Chain
-    from langchain.prompts import PromptTemplate
-    from langchain.schema.language_model import BaseLanguageModel
-
 
 def create_data_generation_chain(
     llm: BaseLanguageModel,