Relax type annotation for custom input/output types (#12300)

This is needed to be able to do stuff like:

```python
runnable.with_types(input_type=List[str])
```

libs/langchain/langchain/schema/runnable/base.py

@@ -2367,9 +2367,10 @@ class RunnableBinding(RunnableSerializable[Input, Output]):
 
     config: RunnableConfig = Field(default_factory=dict)
 
-    custom_input_type: Optional[Union[Type[Input], BaseModel]] = None
+    # Union[Type[Input], BaseModel] + things like List[str]
-
+    custom_input_type: Optional[Any] = None
-    custom_output_type: Optional[Union[Type[Output], BaseModel]] = None
+    # Union[Type[Output], BaseModel] + things like List[str]
+    custom_output_type: Optional[Any] = None
 
     class Config:
         arbitrary_types_allowed = True

libs/langchain/tests/unit_tests/schema/runnable/test_runnable.py

@@ -557,6 +557,22 @@ def test_lambda_schemas() -> None:
     }
 
 
+def test_with_types_with_type_generics() -> None:
+    """Verify that with_types works if we use things like List[int]"""
+
+    def foo(x: int) -> None:
+        """Add one to the input."""
+        raise NotImplementedError()
+
+    # Try specifying some
+    RunnableLambda(foo).with_types(
+        output_type=List[int], input_type=List[int]  # type: ignore
+    )
+    RunnableLambda(foo).with_types(
+        output_type=Sequence[int], input_type=Sequence[int]  # type: ignore[arg-type]
+    )
+
+
 def test_schema_complex_seq() -> None:
     prompt1 = ChatPromptTemplate.from_template("what is the city {person} is from?")
     prompt2 = ChatPromptTemplate.from_template(