Bug filtering with not equal operator in astra

[basoko]

Describe the bug

When applying an haystack not equal filter != this is mapped to an invalid astra filter operator $neq. Based on the astra documentation https://docs.datastax.com/en/astra-db-serverless/api-reference/overview.html the correct operator should be $ne.

This produces the following error:

astrapy.core.api.APIRequestError: {"errors":[{"message":"Unsupported filter operator: $neq","errorCode":"UNSUPPORTED_FILTER_OPERATION"}]}

To Reproduce

import os
from haystack_integrations.document_stores.astra import AstraDocumentStore

collection_name = os.getenv("COLLECTION_NAME", "haystack_vector_search")
document_store = AstraDocumentStore(
    collection_name=collection_name,
)
document_store.filter_documents({
    "field": "meta",
    "operator": "!=",
    "value": {
        "file_path": "/workspace/astra-haystack/examples/data/usr_01.txt",
        "source_id": "5b2d27de79bba97da6fc446180d0d99e1024bc7dd6a757037f0934162cfb0916",
    },
})

Steps to reproduce the behavior. Feel free to link a Colab we can run to investigate the issue.

Describe your environment (please complete the following information):

• OS: [e.g. iOS]
• Haystack version: 2.x
• Integration version: 0.8.0