Improve API Key Management by using Google Colab Secrets

[maxploter]

Is your feature request related to a problem? Please describe.
Currently, the tutorials in this project require users to manage API keys by creating local files (nebius_api_key, openai_api_key) and then manually uploading these files to their Google Colab environment. This process has a few drawbacks:

• Repetitive Uploads
• Potential Security Concerns

I propose updating the notebooks to use Google Colab's built-in "Secrets" feature for managing API keys as an alternative to current file based solution. This feature allows users to store sensitive data like API keys directly within their Colab environment, accessible via the google.colab.userdata module. Secrets are tied to the user's Google account and persist across Colab sessions for that user.

try:
    from google.colab import userdata
    IS_COLAB = True
except ImportError:
    IS_COLAB = False

import os

if not IS_COLAB:
  with open("nebius_api_key", "r") as file:
      nebius_api_key = file.read().strip()

  os.environ["NEBIUS_API_KEY"] = nebius_api_key

  with open("openai_api_key", "r") as file:
      openai_api_key = file.read().strip()

  os.environ["OPENAI_API_KEY"] = openai_api_key

if IS_COLAB:
    nebius_api_key = userdata.get("nebius_api_key")
    os.environ["NEBIUS_API_KEY"] = nebius_api_key
    print("Nebius API key loaded from Colab secrets.")

    openai_api_key = userdata.get("openai_api_key")
    os.environ["OPENAI_API_KEY"] = openai_api_key
    print("OpenAI API key loaded from Colab secrets.")