test: Add required cache_write_tokens field

[alexander-alderman-webb]

Description

The field became required in openai version 2.45.0.

Issues

Reminders

• Please add tests to validate your changes, and lint your code using uv run ruff.
• Add GH Issue ID & Linear ID (if applicable)
• PR title should use conventional commit style (feat:, fix:, ref:, meta:)
• For external contributors: CONTRIBUTING.md, Sentry SDK development docs, Discord community

[github-actions]

Codecov Results 📊

✅ 91020 passed | ⏭️ 6302 skipped | Total: 97322 | Pass Rate: 93.52% | Execution Time: 316m 8s

📊 Comparison with Base Branch

Metric	Change
Total Tests	—
Passed Tests	—
Failed Tests	—
Skipped Tests	—

✨ No test changes detected

All tests are passing successfully.

✅ Patch coverage is 100.00%. Project has 2439 uncovered lines.
✅ Project coverage is 89.79%. Comparing base (base) to head (head).

Coverage diff

@@            Coverage Diff             @@
##          main       #PR       +/-##
==========================================
+ Coverage    89.76%    89.79%    +0.03%
==========================================
  Files          193       193         —
  Lines        23888     23888         —
  Branches      8250      8250         —
==========================================
+ Hits         21442     21449        +7
- Misses        2446      2439        -7
- Partials      1353      1353         —

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