Remove pickling demo and include other minor fixes

[jaggiK]

This PR addresses the following updates:

Removal of Pickling Demo: The demo for pickling states has been removed as it is currently broken. Dependencies: Included a pip install instruction for Adalflow to streamline dependencies. Import Fixes: Fixed import issues for Parameter and Sequential to ensure compatibility and proper functionality. OpenAI API Key Entry: Enabled API key entry via keyboard input, aligning with the interaction method in other notebooks.

Testing: This PR has been tested successfully on both a local machine and Google Colab to verify functionality.

Notes: The pickling demo can be reintroduced in the future once the issues are resolved. More on this issue can be found here

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[jaggiK]

Could you provide further clarification on the third point? I've made some changes based on my understanding, let me know if I've misinterpreted the requirement.

[fm1320]

@jaggiK Hi, basically you need to edit the docs/source/tutorials files so that the links appear as part of the documentation. So that they appear here like open in colab:

More info in the contributing guide here: https://adalflow.sylph.ai/contributor/contribution.html

[liyin2015]

@fm1320 could you merge this and we will add the links ourselves so that we can move this pr faster

[jaggiK]

Just pushed a modification. Not sure if this is as expected. Let me know, I am happy to revert or feel free to override.