fix: Inconsistent use of v3 and v4 Weaviate clients

[chrisk314]

Description

This PR addresses #13614 which relates to inconsistencies between Weaviate V3 and V4 clients in the llama-index-vector-stores-weaviate implementation. This causes bugs due to breaking API changes between V3 and V4.

All references to Weaviate V3 clients (weaviate.Client) have been changed to Weaviate V4 clients (weaviate.WeaviateClient). The current implementation expects Weaviate V4 clients. Documentation has also been modified to reflect changes.

Additionally, the auth_config argument to WeaviateVectorStore.from_params has been made optional to match the underlying weaviate.WeaviateClient signature.

Fixes #13614

Version Bump?

Did I bump the version in the pyproject.toml file of the package I am updating? (Except for the llama-index-core package)

• Yes
• No

Type of Change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

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

• Added new unit/integration tests
• Added new notebook (that tests end-to-end)
• I stared at the code and made sure it makes sense

I manually tested the code against a locally running Weaviate database instance. Specifically, I have run the updated example code in the WeaviateVectorStore docstring (changing the Weaviate url as required); and I have manually tested the modified WeaviateVectorStore.from_params method with the same url. Due to the fact that adequately testing the code requires Weaviate infrastructure to test against, and no pattern is currently in place for such integration tests, I have not attempted to add such integration tests in this set of changes.

Suggested Checklist:

• 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
• I have added Google Colab support for the newly added notebooks.
• 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
• I ran make format; make lint to appease the lint gods

[chrisk314]

Requires review of existing documentation related to Weaviate integration and potential modification of examples to use V4 Weaviate clients.

[RubenGres]

Is this PR planned to be merged ? It has been five months.