Fix: Update OpenAIEmbedder to support reduced embedding dimensions (sync with Chroma)

[haroon0x]

Description

Issue #1229: Mem0 fails when trying to reduce OpenAI embedding dimensions (e.g., 1024) because vector_dimension in the config was never passed to Chroma's OpenAIEmbeddingFunction.

Fixes # (issue)
#1229
This PR updates Mem0’s OpenAIEmbedder to forward vector_dimension from the config to Chroma, so embedding dimensions work correctly.

vector_dimension = self.config.vector_dimension or VectorDimensions.OPENAI.value
embedding_fn = OpenAIEmbeddingFunction(
    api_key=api_key,
    api_base=api_base,
    organization_id=os.getenv("OPENAI_ORGANIZATION"),
    model_name=self.config.model,
    dimensions=vector_dimension, #  added 
)
self.set_embedding_fn(embedding_fn=embedding_fn)
self.set_vector_dimension(vector_dimension=vector_dimension)

Type of change

Please delete options that are not relevant.

• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

How Has This Been Tested?

• Unit Test
• Test Script (please provide)

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 Reduce Dimensions of new OpenAI embedding models is not working #1229
• Made sure Checks passed

[CLAassistant]

All committers have signed the CLA.