fix(retrieve): call with_tenant on collection before query

[RA1NCS]

Summary

Calling multi-tenant hybrid search in WeaviateRM raised
AttributeError: '_QueryCollection' object has no attribute 'with_tenant'.
This PR fixes the bug by scoping the collection first (collection.with_tenant(...)) before executing .query.hybrid(...).

Root cause

The v4 Python client exposes with_tenant() on Collection, not on the
_QueryCollection helper returned by collection.query.
Current code path:

# buggy – AttributeError
collection.query.with_tenant(tenant).hybrid(...)

Fix

# fixed – tenant scoping first, then query
collection.with_tenant(tenant).query.hybrid(...)

How to reproduce the original bug

client = weaviate.connect_to_weaviate_cloud(
    cluster_url=os.environ["WEAVIATE_URL"],
    auth_credentials=Auth.api_key(os.environ["WEAVIATE_API_KEY"]),
)

rm = WeaviateRM(
    weaviate_client=client,
    weaviate_collection_name="test-collection",
    tenant_id="dev",
)

# raises AttributeError on current main
rm("What is the capital of France?")

What’s in this PR

• Single-line change in dspy/retrieve/weaviate_rm.py (no other files touched).

Test & lint status

Step	Result
pre-commit run --all-files	✅ passed
uv run pytest (macOS, Python 3.10)	✅ 402 passed, 222 skipped, 2 xfail

pytest summary

402 passed, 222 skipped, 2 xfailed, 12 warnings in 76.9 s

Checklist

• Follows Contribution Guide.
• Only necessary source change; no lockfile or version bumps.
• Pre-commit hooks clean.
• Full test suite passes locally.
• Unit tests added/updated if needed (N/A – existing retrieval tests exercised path).
• Docs updated (N/A).

Related issues

Notes for reviewers

This unblocks multi-tenant RAG flows with the v4 Weaviate Python client.