CompatHelper: bump compat for OhMyThreads to 0.8, (keep existing compat)

[github-actions]

This pull request changes the compat entry for the OhMyThreads package from 0.6, 0.7 to 0.6, 0.7, 0.8.
This keeps the compat entries for earlier versions.

Note: I have not tested your package with this new compat entry.
It is your responsibility to make sure that your package tests pass before you merge this pull request.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 99.79%. Comparing base (aa882e9) to head (5891f73).
Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #71   +/-   ##
=======================================
  Coverage   99.79%   99.79%           
=======================================
  Files          16       16           
  Lines         480      480           
=======================================
  Hits          479      479           
  Misses          1        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.