CompatHelper: bump compat for QuantumToolbox to 0.20, (keep existing compat)

[github-actions]

This pull request changes the compat entry for the QuantumToolbox package from 0.15 - 0.19 to 0.15 - 0.19, 0.20.
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 91.98%. Comparing base (611e498) to head (4b8e9a6).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #114   +/-   ##
=======================================
  Coverage   91.98%   91.98%           
=======================================
  Files          23       23           
  Lines        1459     1459           
=======================================
  Hits         1342     1342           
  Misses        117      117           

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