Resolved a few deprecation warnings

[jamesbraza]

Seen in pytest logs after #920:

tests/test_clients.py: 422 warnings
tests/test_agents.py: 281 warnings
  /path/to/paper-qa/paperqa/clients/semantic_scholar.py:207: PydanticDeprecatedSince211: Accessing this attribute on the instance is deprecated, and will be removed in Pydantic V3. Instead, you should access this attribute from the model class. Deprecated in Pydantic V2.11 to be removed in V3.0.
    if key not in doc_details.model_fields:

tests/test_clients.py: 691 warnings
tests/test_agents.py: 367 warnings
tests/test_paperqa.py: 7 warnings
  /path/to/paper-qa/paperqa/clients/crossref.py:230: PydanticDeprecatedSince211: Accessing this attribute on the instance is deprecated, and will be removed in Pydantic V3. Instead, you should access this attribute from the model class. Deprecated in Pydantic V2.11 to be removed in V3.0.
    if key not in doc_details.model_fields:

Also this one from litellm:

.venv/lib/python3.12/site-packages/litellm/caching/llm_caching_handler.py:18: 12 warnings
  /Users/jamesbraza/code/paper-qa/.venv/lib/python3.12/site-packages/litellm/caching/llm_caching_handler.py:18: DeprecationWarning: There is no current event loop
    event_loop = asyncio.get_event_loop()

This PR also documents a py.typed issue for openreview-py

[Copilot]

Pull Request Overview

This PR addresses Pydantic deprecation warnings by updating attribute access for model_fields in client modules and documents a known issue with openreview-py in the pyproject.toml file.

• Change 1: Accessing model_fields via type(doc_details) instead of via the instance in both semantic_scholar.py and crossref.py.
• Change 2: Adding an inline comment in pyproject.toml to document an openreview-py issue.

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
pyproject.toml	Added a comment for openreview-py to document a related issue
paperqa/clients/semantic_scholar.py	Updated attribute access to model_fields via type(doc_details)
paperqa/clients/crossref.py	Updated attribute access to model_fields via type(doc_details)