fix: dependencies

[cachho]

Description

Streamlines dependencies.

• delete setup.py - only use pyproject.toml for easier maintainability
• add pip install embedchain[opensource] for the open source app
• raise custom error

Potential problems:

• the open source dependencies are huge. Since we run poetry install --all-extras in the CI script, this might make CI slow, on my local machine it takes around 20 minutes, in the worst case it might be too much for the free tier of github. In this case we might have to change the CI script.

Fixes #392
Fixes #335

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• Refactor (does not change functionality, e.g. code style improvements, linting)

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce. Please also list any relevant details for your test configuration

Please delete options that are not relevant.

• Unit Test
• Test Script (please provide)

from embedchain import OpenSourceApp

app = OpenSourceApp()
app.add("text", "lorem ipsum")

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules
• I have checked my code and corrected any misspellings

Maintainer Checklist

• closes #xxxx (Replace xxxx with the GitHub issue number)
• Made sure Checks passed

[taranjeet]

Looks good to me. @cachho : can you fix the conflict? can merge post that.