added missing embedding_function param in get_or_create_collection

[shivankar-p]

Description of changes

Added a missing param(embedding_function) for get_or_create_collection as mentioned in #304

[shivankar-p]

Thank you! Can we add tests for get_or_create_collection with embedding functions?

Sure. I'll add them

[shivankar-p]

@HammadB I guess the tests are already included for get_or_create_collection with embedding functions. The only change made here was that the abstract class function signature didn't match with the actual implementation.

[HammadB]

@shivankar-p Right now the test doesn't check if the embeddings themselves are the same, just that they exist by looking at the len() could you add that?

[shivankar-p]

@HammadB does the latest commit look good? If this is fine I will update similarly for other tests like get_collection etc. because they are also just tested on len()

[HammadB]

Thank you - This looks great! I think we can tackle that on a separate PR if you are up for that!