build: bump azure-cosmos from 4.5.0 to 4.9.0 in /ResearchAssistant/App

Bumps [azure-cosmos](https://github.com/Azure/azure-sdk-for-python) from 4.5.0 to 4.9.0.
- [Release notes](https://github.com/Azure/azure-sdk-for-python/releases)
- [Changelog](https://github.com/Azure/azure-sdk-for-python/blob/main/doc/esrp_release.md)
- [Commits](Azure/azure-sdk-for-python@azure-cosmos_4.5.0...azure-cosmos_4.9.0)

---
updated-dependencies:
- dependency-name: azure-cosmos
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

ResearchAssistant/App/requirements.txt

@@ -4,7 +4,7 @@ openai==1.58.1
 azure-search-documents==11.4.0b6
 azure-storage-blob==12.17.0
 python-dotenv==1.0.1
-azure-cosmos==4.5.0
+azure-cosmos==4.9.0
 pytest-asyncio==0.25.0
 pytest-cov==5.0.0
 flake8==7.1.1