Move test deps to a group

[mdekstrand]

This moves the test dependencies from an extra to a group.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 89.97%. Comparing base (4e50da7) to head (effe518).
Report is 170 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #662      +/-   ##
==========================================
+ Coverage   89.96%   89.97%   +0.01%     
==========================================
  Files         124      124              
  Lines        8649     8652       +3     
==========================================
+ Hits         7781     7785       +4     
+ Misses        868      867       -1     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.