Add fastapi, httpx, and hypothesis to test dependencies

[Copilot]

Description

tests/server_test.py and tests/server_fuzz_test.py fail with ModuleNotFoundError: No module named 'fastapi' because the packages they require were absent from the [test] extras in pyproject.toml.

Changes:

• pyproject.toml: Add fastapi>=0.111.0, httpx>=0.27.0, and hypothesis>=6.100.0 to [project.optional-dependencies] test
  • fastapi — direct import (from fastapi.testclient import TestClient) in both server test files
  • httpx — runtime requirement of FastAPI's TestClient
  • hypothesis — property-based fuzz testing in server_fuzz_test.py

Versions align with what is already pinned in server/requirements.txt. CI installs via pip install -e ".[dev,test]", so these are now included automatically.

Bug fix

How Has This Been Tested?

$ python -m pytest tests/server_test.py tests/server_fuzz_test.py -q
61 passed in 16.23s

Checklist:

• I have read and acknowledged Google's Open Source
  Code of conduct.
• I have read the
  Contributing
  page, and I either signed the Google
  Individual CLA
  or am covered by my company's
  Corporate CLA.
• I have discussed my proposed solution with code owners in the linked
  issue(s) and we have agreed upon the general approach.
• I have made any needed documentation changes, or noted in the linked
  issue(s) that documentation elsewhere needs updating.
• I have added tests, or I have ensured existing tests cover the changes
• I have followed
  Google's Python Style Guide
  and ran pylint over the affected code.

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• generativelanguage.googleapis.com
  • Triggering command: /usr/bin/python python -m pytest tests/server_test.py tests/server_fuzz_test.py -x -q (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

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