Show end time correctly in HTML report

[andrea-pasquale]

Currently in the report start time and end time were the same due to a small bug.
This PR fixes the issue.

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

All modified and coverable lines are covered by tests ✅

Project coverage is 97.19%. Comparing base (808e23f) to head (954a7d8).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #795   +/-   ##
=======================================
  Coverage   97.19%   97.19%           
=======================================
  Files         104      104           
  Lines        7567     7567           
=======================================
  Hits         7355     7355           
  Misses        212      212           

Flag	Coverage Δ
unittests	97.19% <100.00%> (ø)

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Files	Coverage Δ
src/qibocal/cli/autocalibration.py	100.00% <100.00%> (ø)