ci: Remove asttokens from requirements-testing.txt

[alexander-alderman-webb]

Description

Remove the package from requirements-testing.txt and add the package as a dependency to only the test suites that rely on the package (if applicable).

This is part of environment cleanup before moving the remaining testing dependencies to a uv dependency group.

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 📊

✅ 90151 passed | ⏭️ 6305 skipped | Total: 96456 | Pass Rate: 93.46% | Execution Time: 317m 30s

📊 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 2397 uncovered lines.
✅ Project coverage is 89.93%. Comparing base (base) to head (head).

Coverage diff

@@            Coverage Diff             @@
##          main       #PR       +/-##
==========================================
+ Coverage    89.90%    89.93%    +0.03%
==========================================
  Files          192       192         —
  Lines        23809     23809         —
  Branches      8218      8218         —
==========================================
+ Hits         21404     21412        +8
- Misses        2405      2397        -8
- Partials      1341      1339        -2

---

Generated by Codecov Action

[ericapisani]

LGTM