Convert frequency from GHz to Hz in qubit flux dependence

[andrea-pasquale]

This PR fixes a factor 10^9 which was wrong in qubit flux dependence.
@Edoardo-Pedicillo @GabrielePalazzo let's try to merge this before the release
Checklist:

• Reviewers confirm new code works as expected.
• Tests are passing.
• Coverage does not decrease.
• Documentation is updated.
• Compatibility with Qibo modules (Please edit this section if the current pull request is not compatible with the following branches).
  • Qibo: master
  • Qibolab: main
  • Qibolab_platforms_qrc: main

[codecov]

Codecov Report

Merging #657 (d1112d7) into main (ae9d1e6) will decrease coverage by 0.07%.
Report is 20 commits behind head on main.
The diff coverage is 0.00%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #657      +/-   ##
==========================================
- Coverage   96.09%   96.02%   -0.07%     
==========================================
  Files         106      106              
  Lines        7350     7350              
==========================================
- Hits         7063     7058       -5     
- Misses        287      292       +5     

Flag	Coverage Δ
unittests	96.02% <0.00%> (-0.07%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
.../characterization/allxy/allxy_drag_pulse_tuning.py	100.00% <ø> (ø)
...tocols/characterization/allxy/drag_pulse_tuning.py	100.00% <ø> (ø)
...erization/flux_dependence/qubit_flux_dependence.py	88.81% <0.00%> (ø)

... and 2 files with indirect coverage changes

[andrea-pasquale]

@scarrazza now that tests are passing I will merge and you are free to make a release also for qibocal.

[scarrazza]

Thanks @andrea-pasquale.