How to fix `transformers` package not found error in a Python project with `py-langchain`, `llama-index`, and `gradio`?

I get this error ModuleNotFoundError: No module named 'transformers' even though I did the pip install transformers command. Could you kindly help me? Thank you

My code:

import os
import sys
from dotenv import load_dotenv
import gradio as gr
from langchain import OpenAI
from llama_index import SimpleDirectoryReader, GPTListIndex, GPTVectorStoreIndex, LLMPredictor, PromptHelper
##from transformers import pipeline

load_dotenv()

os.environ['OPENAI_API_KEY'] = os.getenv('OPENAI_API_KEY') 

def construct_index(directory_path):
    max_input_size = 4096
    num_outputs = 512
    max_chunk_overlap = 20
    chunk_size_limit = 600

    prompt_helper = PromptHelper(max_input_size, num_outputs, max_chunk_overlap, chunk_size_limit=chunk_size_limit)

    llm_predictor = LLMPredictor(llm=OpenAI(temperature=0.7, model_name="text-davinci-003", max_tokens=num_outputs))

    documents = SimpleDirectoryReader(directory_path).load_data()

    index = GPTVectorStoreIndex(documents, llm_predictor=llm_predictor, prompt_helper=prompt_helper)

    index.save_to_disk('index.json')

    return index

def qabot(input_text):
    index = GPTVectorStoreIndex.load_from_disk('index.json')
    response = index.query(input_text, response_mode="compact")
    return response.response

iface = gr.Interface(fn=qabot, inputs=gr.inputs.Textbox(lines=7, label='Enter you query'), outputs="text", title="Custom-trained QA Application")

index = construct_index("docs")

iface.launch(share=True)

Maybe you can uncomment

##from transformers import pipeline