Breaking change in `weaviate-client`

[LukasWestholt]

The dependency weaviate-client got an (for us) breaking change:

A refactoring of the underlying implementation of the WeaviateClient to use the WeaviateAsyncClient under-the-hood scheduling the necessary coroutines to run in a side-car event-loop thread

(see https://weaviate-python-client.readthedocs.io/en/stable/changelog.html#version-4-7-0)

The event-loop thread (Singleton) in WeaviateClient prevents parallel upload > 1 from working. Because only one instance of the .connect() class is allowed at any one time.

See weaviate/weaviate-python-client#1007

So for a hotfix i will prepare a new version constraint for weaviate-client.

[LukasWestholt]

After merging, we have to think about migrating WeaviateClient to WeaviateAsyncClient, right? @trengrj