AttributeError: 'super' object has no attribute 'parse_obj'

1. My Versons:
On my laptop, I installed openapi_schema_pydantic (1.2.4). Now I have

langchain 0.0.353
langchain-cli 0.0.21
langchain-community 0.0.16
langchain-core 0.1.16
langchain-openai 0.0.5
langchainhub 0.1.14
pydantic 2.6.2
pydantic_core 2.16.3
openapi-schema-pydantic 1.2.4

2. My Code:
Added openapi_schema_pydantic import compared to Instructor’s code, as learnt from above posts, and https://pypi.org/project/openapi-schema-pydantic/.

from langchain.chains.openai_functions.openapi import openapi_spec_to_openai_fn
from langchain.utilities.openapi import OpenAPISpec
from openapi_schema_pydantic import OpenAPI, Info, PathItem, Operation, Response ← added this
text = “”"

“”"
spec = OpenAPISpec.from_text(text)

3. My Error:
Instructor code did not err, but mine did. Different error message compared to others in this post.

PydanticUserError: const is removed, use Literal instead
For further information visit Redirecting...

What am I missing, especially when the same code seems to be working for others? How do I overcome the error?