ci: Replace requirements-testing.txt with a uv dependency group

[alexander-alderman-webb]

Description

Complete the transition to uv based workflows, allowing for consistent dependency pinning of common testing dependencies like pytest.

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 📊

✅ 89883 passed | ⏭️ 6297 skipped | Total: 96180 | Pass Rate: 93.45% | Execution Time: 311m 58s

📊 Comparison with Base Branch

Metric	Change
Total Tests	📈 +41
Passed Tests	📈 +41
Failed Tests	—
Skipped Tests	—

All tests are passing successfully.

✅ Patch coverage is 100.00%. Project has 2441 uncovered lines.
✅ Project coverage is 89.75%. Comparing base (base) to head (head).

Coverage diff

@@            Coverage Diff             @@
##          main       #PR       +/-##
==========================================
+ Coverage    89.75%    89.75%        —%
==========================================
  Files          192       192         —
  Lines        23809     23809         —
  Branches      8218      8218         —
==========================================
+ Hits         21367     21368        +1
- Misses        2442      2441        -1
- Partials      1347      1346        -1

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Generated by Codecov Action

[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

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[sl0thentr0py]

thx, i forgot to do this earlier